diff --git a/lucene/core/src/java/org/apache/lucene/util/BytesRef.java b/lucene/core/src/java/org/apache/lucene/util/BytesRef.java
index 1fbdaf95412d..7f08f8b776e4 100644
--- a/lucene/core/src/java/org/apache/lucene/util/BytesRef.java
+++ b/lucene/core/src/java/org/apache/lucene/util/BytesRef.java
@@ -16,6 +16,7 @@
  */
 package org.apache.lucene.util;
 
+import java.nio.ByteBuffer;
 import java.util.Arrays;
 
 /**
@@ -211,4 +212,8 @@ public boolean isValid() {
     }
     return true;
   }
+
+  public ByteBuffer wrapToByteBuffer() {
+    return ByteBuffer.wrap(bytes, offset, length);
+  }
 }
diff --git a/solr/core/src/java/org/apache/solr/handler/admin/LukeRequestHandler.java b/solr/core/src/java/org/apache/solr/handler/admin/LukeRequestHandler.java
index 67b60090536a..7e5447eaaacd 100644
--- a/solr/core/src/java/org/apache/solr/handler/admin/LukeRequestHandler.java
+++ b/solr/core/src/java/org/apache/solr/handler/admin/LukeRequestHandler.java
@@ -18,9 +18,11 @@
 
 import java.io.IOException;
 import java.lang.invoke.MethodHandles;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.NoSuchFileException;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Base64;
 import java.util.Date;
 import java.util.HashMap;
 import java.util.LinkedList;
@@ -66,7 +68,6 @@
 import org.apache.solr.common.luke.FieldFlag;
 import org.apache.solr.common.params.CommonParams;
 import org.apache.solr.common.params.SolrParams;
-import org.apache.solr.common.util.Base64;
 import org.apache.solr.common.util.NamedList;
 import org.apache.solr.common.util.SimpleOrderedMap;
 import org.apache.solr.handler.RequestHandlerBase;
@@ -298,7 +299,7 @@ private static SimpleOrderedMap<Object> getDocumentFieldsInfo( Document doc, int
 
       BytesRef bytes = field.binaryValue();
       if (bytes != null) {
-        f.add( "binary", Base64.byteArrayToBase64(bytes.bytes, bytes.offset, bytes.length));
+        f.add( "binary", new String(Base64.getEncoder().encode(bytes.wrapToByteBuffer()).array(), StandardCharsets.ISO_8859_1));
       }
       if (!ftype.isPointField()) {
         Term t = new Term(field.name(), ftype!=null ? ftype.storedToIndexed(field) : field.stringValue());
diff --git a/solr/core/src/java/org/apache/solr/handler/admin/MetricsHistoryHandler.java b/solr/core/src/java/org/apache/solr/handler/admin/MetricsHistoryHandler.java
index 4aae15b4f0f4..64da8490150e 100644
--- a/solr/core/src/java/org/apache/solr/handler/admin/MetricsHistoryHandler.java
+++ b/solr/core/src/java/org/apache/solr/handler/admin/MetricsHistoryHandler.java
@@ -29,6 +29,7 @@
 import java.net.URL;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Base64;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
@@ -75,7 +76,6 @@
 import org.apache.solr.common.params.CommonParams;
 import org.apache.solr.common.params.ModifiableSolrParams;
 import org.apache.solr.common.params.SolrParams;
-import org.apache.solr.common.util.Base64;
 import org.apache.solr.common.util.ExecutorUtil;
 import org.apache.solr.common.util.JavaBinCodec;
 import org.apache.solr.common.util.NamedList;
@@ -948,7 +948,7 @@ private NamedList<Object> getDbData(RrdDb db, String[] dsNames, Format format, S
             graph.render(bi.getGraphics());
             ByteArrayOutputStream baos = new ByteArrayOutputStream();
             ImageIO.write(bi, "png", baos);
-            values.add(name, Base64.byteArrayToBase64(baos.toByteArray()));
+            values.add(name, Base64.getEncoder().encodeToString(baos.toByteArray()));
             break;
           case STRING:
             str.setLength(0);
diff --git a/solr/core/src/java/org/apache/solr/handler/component/TermVectorComponent.java b/solr/core/src/java/org/apache/solr/handler/component/TermVectorComponent.java
index f28e6e3e62c3..030ee4154a56 100644
--- a/solr/core/src/java/org/apache/solr/handler/component/TermVectorComponent.java
+++ b/solr/core/src/java/org/apache/solr/handler/component/TermVectorComponent.java
@@ -17,8 +17,10 @@
 package org.apache.solr.handler.component;
 
 import java.io.IOException;
+import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Base64;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.Iterator;
@@ -39,7 +41,6 @@
 import org.apache.solr.common.params.CommonParams;
 import org.apache.solr.common.params.SolrParams;
 import org.apache.solr.common.params.TermVectorParams;
-import org.apache.solr.common.util.Base64;
 import org.apache.solr.common.util.NamedList;
 import org.apache.solr.core.SolrCore;
 import org.apache.solr.schema.IndexSchema;
@@ -366,7 +367,7 @@ private void mapOneVector(NamedList<Object> docNL, FieldOptions fieldOptions, In
               thePayloads = new NamedList<>();
               termInfo.add("payloads", thePayloads);
             }
-            thePayloads.add("payload", Base64.byteArrayToBase64(payload.bytes, payload.offset, payload.length));
+            thePayloads.add("payload", new String(Base64.getEncoder().encode(payload.wrapToByteBuffer()).array(), StandardCharsets.ISO_8859_1));
           }
         }
       }
diff --git a/solr/core/src/java/org/apache/solr/schema/BinaryField.java b/solr/core/src/java/org/apache/solr/schema/BinaryField.java
index 8951e9e2ee58..094a219fe168 100644
--- a/solr/core/src/java/org/apache/solr/schema/BinaryField.java
+++ b/solr/core/src/java/org/apache/solr/schema/BinaryField.java
@@ -19,12 +19,13 @@
 import java.io.IOException;
 import java.lang.invoke.MethodHandles;
 import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
+import java.util.Base64;
 
 import org.apache.lucene.index.IndexableField;
 import org.apache.lucene.search.SortField;
 import org.apache.lucene.util.BytesRef;
 import org.apache.solr.common.SolrException;
-import org.apache.solr.common.util.Base64;
 import org.apache.solr.response.TextResponseWriter;
 import org.apache.solr.uninverting.UninvertingReader.Type;
 import org.slf4j.Logger;
@@ -44,7 +45,7 @@ public void checkSchemaField(SchemaField field) {
   }
 
   private String toBase64String(ByteBuffer buf) {
-    return Base64.byteArrayToBase64(buf.array(), buf.position(), buf.limit()-buf.position());
+    return new String(Base64.getEncoder().encode(buf).array(), StandardCharsets.ISO_8859_1);
   }
 
   @Override
@@ -98,7 +99,7 @@ public IndexableField createField(SchemaField field, Object val) {
     } else {
       String strVal = val.toString();
       //the string has to be a base64 encoded string
-      buf = Base64.base64ToByteArray(strVal);
+      buf = Base64.getDecoder().decode(strVal);
       offset = 0;
       len = buf.length;
     }
@@ -112,7 +113,7 @@ public Object toNativeType(Object val) {
       return ByteBuffer.wrap((byte[]) val);
     } else if (val instanceof CharSequence) {
       final CharSequence valAsCharSequence = (CharSequence) val;
-      return ByteBuffer.wrap(Base64.base64ToByteArray(valAsCharSequence.toString()));
+      return ByteBuffer.wrap(Base64.getDecoder().decode(valAsCharSequence.toString()));
     }
     return super.toNativeType(val);
   }
diff --git a/solr/core/src/java/org/apache/solr/schema/FieldType.java b/solr/core/src/java/org/apache/solr/schema/FieldType.java
index c29eecc95960..75e450c6bea0 100644
--- a/solr/core/src/java/org/apache/solr/schema/FieldType.java
+++ b/solr/core/src/java/org/apache/solr/schema/FieldType.java
@@ -18,7 +18,9 @@
 
 import java.io.IOException;
 import java.lang.invoke.MethodHandles;
+import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
+import java.util.Base64;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
@@ -67,7 +69,6 @@
 import org.apache.solr.common.IteratorWriter;
 import org.apache.solr.common.SolrException;
 import org.apache.solr.common.SolrException.ErrorCode;
-import org.apache.solr.common.util.Base64;
 import org.apache.solr.common.util.SimpleOrderedMap;
 import org.apache.solr.common.util.StrUtils;
 import org.apache.solr.query.SolrRangeQuery;
@@ -1327,7 +1328,7 @@ protected static Object marshalBase64SortValue(Object value) {
       return null;
     }
     final BytesRef val = (BytesRef)value;
-    return Base64.byteArrayToBase64(val.bytes, val.offset, val.length);
+    return new String(Base64.getEncoder().encode(val.wrapToByteBuffer()).array(), StandardCharsets.ISO_8859_1);
   }
 
   /**
@@ -1338,7 +1339,7 @@ protected static Object unmarshalBase64SortValue(Object value) {
       return null;
     }
     final String val = (String)value;
-    final byte[] bytes = Base64.base64ToByteArray(val);
+    final byte[] bytes = Base64.getDecoder().decode(val);
     return new BytesRef(bytes);
   }
 
diff --git a/solr/core/src/java/org/apache/solr/schema/JsonPreAnalyzedParser.java b/solr/core/src/java/org/apache/solr/schema/JsonPreAnalyzedParser.java
index 15a3255f3159..57eb030d50fa 100644
--- a/solr/core/src/java/org/apache/solr/schema/JsonPreAnalyzedParser.java
+++ b/solr/core/src/java/org/apache/solr/schema/JsonPreAnalyzedParser.java
@@ -19,6 +19,8 @@
 import java.io.IOException;
 import java.io.Reader;
 import java.lang.invoke.MethodHandles;
+import java.nio.charset.StandardCharsets;
+import java.util.Base64;
 import java.util.Iterator;
 import java.util.LinkedHashMap;
 import java.util.LinkedList;
@@ -40,7 +42,6 @@
 import org.apache.lucene.util.AttributeSource;
 import org.apache.lucene.util.AttributeSource.State;
 import org.apache.lucene.util.BytesRef;
-import org.apache.solr.common.util.Base64;
 import org.apache.solr.schema.PreAnalyzedField.ParseResult;
 import org.apache.solr.schema.PreAnalyzedField.PreAnalyzedParser;
 import org.noggit.JSONUtil;
@@ -100,7 +101,7 @@ public ParseResult parse(Reader reader, AttributeSource parent)
     res.str = (String)map.get(STRING_KEY);
     String bin = (String)map.get(BINARY_KEY);
     if (bin != null) {
-      byte[] data = Base64.base64ToByteArray(bin);
+      byte[] data = Base64.getDecoder().decode(bin);
       res.bin = data;
     }
     List<Object> tokens = (List<Object>)map.get(TOKENS_KEY);
@@ -166,7 +167,7 @@ public ParseResult parse(Reader reader, AttributeSource parent)
         } else if (key.equals(PAYLOAD_KEY)) {
           String str = String.valueOf(e.getValue());
           if (str.length() > 0) {
-            byte[] data = Base64.base64ToByteArray(str);
+            byte[] data = Base64.getDecoder().decode(str);
             PayloadAttribute p = parent.addAttribute(PayloadAttribute.class);
             if (data != null && data.length > 0) {
               p.setPayload(new BytesRef(data));
@@ -216,7 +217,7 @@ public String toFormattedString(Field f) throws IOException {
       }
       BytesRef binaryValue = f.binaryValue();
       if (binaryValue != null) {
-        map.put(BINARY_KEY, Base64.byteArrayToBase64(binaryValue.bytes, binaryValue.offset, binaryValue.length));
+        map.put(BINARY_KEY, new String(Base64.getEncoder().encode(binaryValue.wrapToByteBuffer()).array(), StandardCharsets.ISO_8859_1));
       }
     }
     TokenStream ts = f.tokenStreamValue();
@@ -248,7 +249,7 @@ public String toFormattedString(Field f) throws IOException {
             } else if (cl.isAssignableFrom(PayloadAttribute.class)) {
               BytesRef p = ((PayloadAttribute)att).getPayload();
               if (p != null && p.length > 0) {
-                tok.put(PAYLOAD_KEY, Base64.byteArrayToBase64(p.bytes, p.offset, p.length));
+                tok.put(PAYLOAD_KEY, new String(Base64.getEncoder().encode(p.wrapToByteBuffer()).array(), StandardCharsets.ISO_8859_1));
               }
             } else if (cl.isAssignableFrom(PositionIncrementAttribute.class)) {
               tok.put(POSINCR_KEY, ((PositionIncrementAttribute)att).getPositionIncrement());
diff --git a/solr/core/src/java/org/apache/solr/search/CursorMark.java b/solr/core/src/java/org/apache/solr/search/CursorMark.java
index 804847141163..8a64788712f2 100644
--- a/solr/core/src/java/org/apache/solr/search/CursorMark.java
+++ b/solr/core/src/java/org/apache/solr/search/CursorMark.java
@@ -26,12 +26,12 @@
 
 import static org.apache.solr.common.params.CursorMarkParams.*;
 
-import org.apache.solr.common.util.Base64;
 import org.apache.solr.common.util.JavaBinCodec;
 import org.apache.solr.schema.IndexSchema;
 import org.apache.solr.schema.FieldType;
 import org.apache.solr.schema.SchemaField;
 
+import java.util.Base64;
 import java.util.List;
 import java.util.ArrayList;
 import java.io.ByteArrayOutputStream;
@@ -183,7 +183,7 @@ public void parseSerializedTotem(final String serialized) {
 
     List<Object> pieces = null;
     try {
-      final byte[] rawData = Base64.base64ToByteArray(serialized);
+      final byte[] rawData = Base64.getDecoder().decode(serialized);
       try (JavaBinCodec jbc = new JavaBinCodec(); ByteArrayInputStream in = new ByteArrayInputStream(rawData)){
         pieces = (List<Object>) jbc.unmarshal(in);
         boolean b = false;
@@ -260,7 +260,7 @@ public String getSerializedTotem() {
     try (JavaBinCodec jbc = new JavaBinCodec(); ByteArrayOutputStream out = new ByteArrayOutputStream(256)) {
       jbc.marshal(marshalledValues, out);
       byte[] rawData = out.toByteArray();
-      return Base64.byteArrayToBase64(rawData, 0, rawData.length);
+      return Base64.getEncoder().encodeToString(rawData);
     } catch (Exception ex) {
       throw new SolrException(ErrorCode.SERVER_ERROR,
                               "Unable to format search after totem", ex);
diff --git a/solr/core/src/java/org/apache/solr/security/JWTAuthPlugin.java b/solr/core/src/java/org/apache/solr/security/JWTAuthPlugin.java
index 8b9271a130ae..410a4aa6a4b4 100644
--- a/solr/core/src/java/org/apache/solr/security/JWTAuthPlugin.java
+++ b/solr/core/src/java/org/apache/solr/security/JWTAuthPlugin.java
@@ -26,6 +26,7 @@
 import java.time.Instant;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Base64;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
@@ -47,7 +48,6 @@
 import org.apache.solr.common.SolrException;
 import org.apache.solr.common.SpecProvider;
 import org.apache.solr.common.StringUtils;
-import org.apache.solr.common.util.Base64;
 import org.apache.solr.common.util.CommandOperation;
 import org.apache.solr.common.util.Utils;
 import org.apache.solr.common.util.ValidatingJsonMap;
@@ -577,7 +577,7 @@ protected String generateAuthDataHeader() {
     data.put("scope", adminUiScope);
     data.put("redirect_uris", redirectUris);
     String headerJson = Utils.toJSONString(data);
-    return Base64.byteArrayToBase64(headerJson.getBytes(StandardCharsets.UTF_8));
+    return Base64.getEncoder().encodeToString(headerJson.getBytes(StandardCharsets.UTF_8));
   }
 
   /**
diff --git a/solr/core/src/java/org/apache/solr/security/PKIAuthenticationPlugin.java b/solr/core/src/java/org/apache/solr/security/PKIAuthenticationPlugin.java
index bdf298f9acc1..3945d67e13d5 100644
--- a/solr/core/src/java/org/apache/solr/security/PKIAuthenticationPlugin.java
+++ b/solr/core/src/java/org/apache/solr/security/PKIAuthenticationPlugin.java
@@ -24,6 +24,7 @@
 import java.nio.ByteBuffer;
 import java.security.Principal;
 import java.security.PublicKey;
+import java.util.Base64;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
@@ -42,7 +43,6 @@
 import org.apache.solr.client.solrj.impl.HttpClientUtil;
 import org.apache.solr.client.solrj.impl.HttpListenerFactory;
 import org.apache.solr.client.solrj.impl.SolrHttpClientBuilder;
-import org.apache.solr.common.util.Base64;
 import org.apache.solr.common.util.ExecutorUtil;
 import org.apache.solr.common.util.StrUtils;
 import org.apache.solr.common.util.SuppressForbidden;
@@ -161,7 +161,7 @@ private PKIHeaderData decipherHeader(String nodeName, String cipherBase64) {
   private static  PKIHeaderData parseCipher(String cipher, PublicKey key) {
     byte[] bytes;
     try {
-      bytes = CryptoKeys.decryptRSA(Base64.base64ToByteArray(cipher), key);
+      bytes = CryptoKeys.decryptRSA(Base64.getDecoder().decode(cipher), key);
     } catch (Exception e) {
       log.error("Decryption failed , key must be wrong", e);
       return null;
@@ -304,7 +304,7 @@ private Optional<String> generateToken() {
 
     byte[] payload = s.getBytes(UTF_8);
     byte[] payloadCipher = publicKeyHandler.keyPair.encrypt(ByteBuffer.wrap(payload));
-    String base64Cipher = Base64.byteArrayToBase64(payloadCipher);
+    String base64Cipher = Base64.getEncoder().encodeToString(payloadCipher);
     log.trace("generateToken: usr={} token={}", usr, base64Cipher);
     return Optional.of(base64Cipher);
   }
diff --git a/solr/core/src/java/org/apache/solr/util/CryptoKeys.java b/solr/core/src/java/org/apache/solr/util/CryptoKeys.java
index 50ca080a2bc7..8e70b906e4fb 100644
--- a/solr/core/src/java/org/apache/solr/util/CryptoKeys.java
+++ b/solr/core/src/java/org/apache/solr/util/CryptoKeys.java
@@ -42,12 +42,12 @@
 import java.security.spec.PKCS8EncodedKeySpec;
 import java.security.spec.X509EncodedKeySpec;
 import java.util.Arrays;
+import java.util.Base64;
 import java.util.HashMap;
 import java.util.Map;
 
 import com.google.common.collect.ImmutableMap;
 import org.apache.solr.common.SolrException;
-import org.apache.solr.common.util.Base64;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -76,7 +76,7 @@ public String verify(String sig, ByteBuffer data) {
     for (Map.Entry<String, PublicKey> entry : keys.entrySet()) {
       boolean verified;
       try {
-        verified = CryptoKeys.verify(entry.getValue(), Base64.base64ToByteArray(sig), data);
+        verified = CryptoKeys.verify(entry.getValue(), Base64.getDecoder().decode(sig), data);
         log.debug("verified {} ", verified);
         if (verified) return entry.getKey();
       } catch (Exception e) {
@@ -94,7 +94,7 @@ public String verify(String sig, InputStream is) {
     for (Map.Entry<String, PublicKey> entry : keys.entrySet()) {
       boolean verified;
       try {
-        verified = CryptoKeys.verify(entry.getValue(), Base64.base64ToByteArray(sig), is);
+        verified = CryptoKeys.verify(entry.getValue(), Base64.getDecoder().decode(sig), is);
         log.debug("verified {} ", verified);
         if (verified) return entry.getKey();
       } catch (Exception e) {
@@ -258,7 +258,7 @@ public static String decodeAES(String base64CipherTxt, String pwd, final int key
     final int CIPHERTEXT_OFFSET = SALT_OFFSET + SALT_SIZE;
 
     try {
-      byte[] headerSaltAndCipherText = Base64.base64ToByteArray(base64CipherTxt);
+      byte[] headerSaltAndCipherText = Base64.getDecoder().decode(base64CipherTxt);
 
       // --- extract salt & encrypted ---
       // header is "Salted__", ASCII encoded, if salt is being used (the default)
@@ -307,7 +307,7 @@ public static String decodeAES(String base64CipherTxt, String pwd, final int key
   public static PublicKey deserializeX509PublicKey(String pubKey) {
     try {
       KeyFactory keyFactory = KeyFactory.getInstance("RSA");
-      X509EncodedKeySpec publicKeySpec = new X509EncodedKeySpec(Base64.base64ToByteArray(pubKey));
+      X509EncodedKeySpec publicKeySpec = new X509EncodedKeySpec(Base64.getDecoder().decode(pubKey));
       return keyFactory.generatePublic(publicKeySpec);
     } catch (Exception e) {
       throw new SolrException(SolrException.ErrorCode.SERVER_ERROR,e);
@@ -349,7 +349,7 @@ public RSAKeyPair() {
       java.security.KeyPair keyPair = keyGen.genKeyPair();
       privateKey = keyPair.getPrivate();
       publicKey = keyPair.getPublic();
-      pubKeyStr = Base64.byteArrayToBase64(publicKey.getEncoded());
+      pubKeyStr = Base64.getEncoder().encodeToString(publicKey.getEncoded());
     }
 
     /**
@@ -365,7 +365,7 @@ public RSAKeyPair(URL privateKeyResourceName, URL publicKeyResourceName) throws
         String privateString = new String(inPrivate.readAllBytes(), StandardCharsets.UTF_8)
             .replaceAll("-----(BEGIN|END) PRIVATE KEY-----", "");
 
-        PKCS8EncodedKeySpec privateSpec = new PKCS8EncodedKeySpec(java.util.Base64.getMimeDecoder().decode(privateString));
+        PKCS8EncodedKeySpec privateSpec = new PKCS8EncodedKeySpec(Base64.getMimeDecoder().decode(privateString));
         KeyFactory rsaFactory = KeyFactory.getInstance("RSA");
         privateKey = rsaFactory.generatePrivate(privateSpec);
       } catch (NoSuchAlgorithmException e) {
@@ -374,7 +374,7 @@ public RSAKeyPair(URL privateKeyResourceName, URL publicKeyResourceName) throws
 
       try (InputStream inPublic = publicKeyResourceName.openStream()) {
         publicKey = getX509PublicKey(inPublic.readAllBytes());
-        pubKeyStr = Base64.byteArrayToBase64(publicKey.getEncoded());
+        pubKeyStr = Base64.getEncoder().encodeToString(publicKey.getEncoded());
       }
     }
 
diff --git a/solr/core/src/test/org/apache/solr/cloud/MetricsHistoryIntegrationTest.java b/solr/core/src/test/org/apache/solr/cloud/MetricsHistoryIntegrationTest.java
index 1a685d69994a..8d5c9435b558 100644
--- a/solr/core/src/test/org/apache/solr/cloud/MetricsHistoryIntegrationTest.java
+++ b/solr/core/src/test/org/apache/solr/cloud/MetricsHistoryIntegrationTest.java
@@ -19,6 +19,7 @@
 import java.io.ByteArrayInputStream;
 import java.io.IOException;
 import java.lang.invoke.MethodHandles;
+import java.util.Base64;
 import java.util.List;
 import java.util.concurrent.TimeUnit;
 
@@ -33,7 +34,6 @@
 import org.apache.solr.common.params.CollectionAdminParams;
 import org.apache.solr.common.params.CommonParams;
 import org.apache.solr.common.params.SolrParams;
-import org.apache.solr.common.util.Base64;
 import org.apache.solr.common.util.NamedList;
 import org.apache.solr.common.util.SimpleOrderedMap;
 import org.apache.solr.common.util.TimeSource;
@@ -172,7 +172,7 @@ public void testGet() throws Exception {
       assertEquals(3, entry.size());
       entry.forEach((vk, vv) -> {
         String valString = (String)vv;
-        byte[] img = Base64.base64ToByteArray(valString);
+        byte[] img = Base64.getDecoder().decode(valString);
         try {
           ImageIO.read(new ByteArrayInputStream(img));
         } catch (IOException e) {
diff --git a/solr/core/src/test/org/apache/solr/handler/component/StatsComponentTest.java b/solr/core/src/test/org/apache/solr/handler/component/StatsComponentTest.java
index b1636d1cc042..41eea09ec5e5 100644
--- a/solr/core/src/test/org/apache/solr/handler/component/StatsComponentTest.java
+++ b/solr/core/src/test/org/apache/solr/handler/component/StatsComponentTest.java
@@ -16,10 +16,12 @@
  */
 package org.apache.solr.handler.component;
 import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
 import java.text.DateFormat;
 import java.text.SimpleDateFormat;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Base64;
 import java.util.Collections;
 import java.util.Date;
 import java.util.EnumSet;
@@ -44,7 +46,6 @@
 import org.apache.solr.common.params.MapSolrParams;
 import org.apache.solr.common.params.SolrParams;
 import org.apache.solr.common.params.StatsParams;
-import org.apache.solr.common.util.Base64;
 import org.apache.solr.common.util.NamedList;
 import org.apache.solr.common.util.StrUtils;
 import org.apache.solr.core.SolrCore;
@@ -1410,7 +1411,7 @@ public void testIndividualStatLocalParams() throws Exception {
                         Collections.singletonList(distinctValsXpath));
     ExpectedStat.createSimple(Stat.countDistinct, "true", "long", "10");
     final String percentileShardXpath = kpre + "str[@name='percentiles'][.='" 
-      + Base64.byteArrayToBase64(tdigestBuf.array(), 0, tdigestBuf.array().length) + "']";
+      + new String(Base64.getEncoder().encode(tdigestBuf.array()), StandardCharsets.ISO_8859_1) + "']";
     final String p90 = "" + tdigest.quantile(0.90D);
     final String p99 = "" + tdigest.quantile(0.99D);
     ExpectedStat.create(Stat.percentiles, "'90, 99'",
@@ -1419,7 +1420,7 @@ public void testIndividualStatLocalParams() throws Exception {
                                       kpre + "lst[@name='percentiles']/double[@name='90.0'][.="+p90+"]",
                                       kpre + "lst[@name='percentiles']/double[@name='99.0'][.="+p99+"]"));
     final String cardinalityShardXpath = kpre + "str[@name='cardinality'][.='" 
-      + Base64.byteArrayToBase64(hllBytes, 0, hllBytes.length) + "']";
+      + new String(Base64.getEncoder().encode(hllBytes),StandardCharsets.ISO_8859_1) + "']";
     final String cardinalityXpath = kpre + "long[@name='cardinality'][.='10']"; 
     ExpectedStat.create(Stat.cardinality, "true",
                         Collections.singletonList(cardinalityShardXpath),
diff --git a/solr/core/src/test/org/apache/solr/security/BasicAuthStandaloneTest.java b/solr/core/src/test/org/apache/solr/security/BasicAuthStandaloneTest.java
index 406ce589b6da..4f198c5cce10 100644
--- a/solr/core/src/test/org/apache/solr/security/BasicAuthStandaloneTest.java
+++ b/solr/core/src/test/org/apache/solr/security/BasicAuthStandaloneTest.java
@@ -22,6 +22,7 @@
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
+import java.util.Base64;
 import java.util.Collections;
 import java.util.Properties;
 
@@ -36,7 +37,6 @@
 import org.apache.solr.client.solrj.impl.HttpClientUtil;
 import org.apache.solr.client.solrj.impl.HttpSolrClient;
 import org.apache.solr.common.params.MapSolrParams;
-import org.apache.solr.common.util.Base64;
 import org.apache.solr.common.util.Utils;
 import org.apache.solr.handler.admin.SecurityConfHandler;
 import org.apache.solr.handler.admin.SecurityConfHandlerLocalForTesting;
@@ -162,7 +162,7 @@ private void doHttpPost(HttpClient cl, String url, String jsonCommand, String ba
 
   public static void setBasicAuthHeader(AbstractHttpMessage httpMsg, String user, String pwd) {
     String userPass = user + ":" + pwd;
-    String encoded = Base64.byteArrayToBase64(userPass.getBytes(UTF_8));
+    String encoded = Base64.getEncoder().encodeToString(userPass.getBytes(UTF_8));
     httpMsg.setHeader(new BasicHeader("Authorization", "Basic " + encoded));
     log.info("Added Basic Auth security Header {}",encoded );
   }
diff --git a/solr/core/src/test/org/apache/solr/security/JWTAuthPluginIntegrationTest.java b/solr/core/src/test/org/apache/solr/security/JWTAuthPluginIntegrationTest.java
index 5351968f1df2..9d211b7c2175 100644
--- a/solr/core/src/test/org/apache/solr/security/JWTAuthPluginIntegrationTest.java
+++ b/solr/core/src/test/org/apache/solr/security/JWTAuthPluginIntegrationTest.java
@@ -24,6 +24,7 @@
 import java.net.HttpURLConnection;
 import java.net.URL;
 import java.nio.charset.StandardCharsets;
+import java.util.Base64;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Set;
@@ -41,7 +42,6 @@
 import org.apache.solr.SolrTestCaseJ4;
 import org.apache.solr.client.solrj.impl.HttpClientUtil;
 import org.apache.solr.cloud.SolrCloudAuthTestCase;
-import org.apache.solr.common.util.Base64;
 import org.apache.solr.common.util.Pair;
 import org.apache.solr.common.util.TimeSource;
 import org.apache.solr.common.util.Utils;
@@ -137,7 +137,7 @@ public void infoRequestValidateXSolrAuthHeaders() throws IOException {
     Map<String, String> headers = getHeaders(baseUrl + "/admin/info/system", null);
     assertEquals("Should have received 401 code", "401", headers.get("code"));
     assertEquals("Bearer realm=\"my-solr-jwt\"", headers.get("WWW-Authenticate"));
-    String authData = new String(Base64.base64ToByteArray(headers.get("X-Solr-AuthData")), UTF_8);
+    String authData = new String(Base64.getDecoder().decode(headers.get("X-Solr-AuthData")), UTF_8);
     assertEquals("{\n" +
         "  \"scope\":\"solr:admin\",\n" +
         "  \"redirect_uris\":[],\n" +
@@ -159,7 +159,7 @@ public void infoRequestValidateXSolrAuthHeadersBlockUnknownFalse() throws Except
     Map<String, String> headers = getHeaders(baseUrl + "/admin/info/system", null);
     assertEquals("Should have received 401 code", "401", headers.get("code"));
     assertEquals("Bearer realm=\"my-solr-jwt-blockunknown-false\"", headers.get("WWW-Authenticate"));
-    String authData = new String(Base64.base64ToByteArray(headers.get("X-Solr-AuthData")), UTF_8);
+    String authData = new String(Base64.getDecoder().decode(headers.get("X-Solr-AuthData")), UTF_8);
     assertEquals("{\n" +
         "  \"scope\":\"solr:admin\",\n" +
         "  \"redirect_uris\":[],\n" +
diff --git a/solr/core/src/test/org/apache/solr/security/JWTAuthPluginTest.java b/solr/core/src/test/org/apache/solr/security/JWTAuthPluginTest.java
index 90713417022f..c42c0e10eb2f 100644
--- a/solr/core/src/test/org/apache/solr/security/JWTAuthPluginTest.java
+++ b/solr/core/src/test/org/apache/solr/security/JWTAuthPluginTest.java
@@ -22,6 +22,7 @@
 import java.nio.file.Path;
 import java.security.Principal;
 import java.util.Arrays;
+import java.util.Base64;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
@@ -30,7 +31,6 @@
 
 import org.apache.solr.SolrTestCaseJ4;
 import org.apache.solr.common.SolrException;
-import org.apache.solr.common.util.Base64;
 import org.apache.solr.common.util.Utils;
 import org.jose4j.jwk.RsaJsonWebKey;
 import org.jose4j.jwk.RsaJwkGenerator;
@@ -442,7 +442,7 @@ public void xSolrAuthDataHeader() {
     testConfig.put("clientId", "solr-cluster");
     plugin.init(testConfig);
     String headerBase64 = plugin.generateAuthDataHeader();
-    String headerJson = new String(Base64.base64ToByteArray(headerBase64), StandardCharsets.UTF_8);
+    String headerJson = new String(Base64.getDecoder().decode(headerBase64), StandardCharsets.UTF_8);
     Map<String,String> parsed = (Map<String, String>) Utils.fromJSONString(headerJson);
     assertEquals("solr:admin", parsed.get("scope"));
     assertEquals("http://acmepaymentscorp/oauth/auz/authorize", parsed.get("authorizationEndpoint"));
diff --git a/solr/solrj/src/java/org/apache/solr/client/solrj/cloud/VersionedData.java b/solr/solrj/src/java/org/apache/solr/client/solrj/cloud/VersionedData.java
index 711411d4a246..003bb83b29d9 100644
--- a/solr/solrj/src/java/org/apache/solr/client/solrj/cloud/VersionedData.java
+++ b/solr/solrj/src/java/org/apache/solr/client/solrj/cloud/VersionedData.java
@@ -18,10 +18,10 @@
 
 import java.io.IOException;
 import java.util.Arrays;
+import java.util.Base64;
 import java.util.Objects;
 
 import org.apache.solr.common.MapWriter;
-import org.apache.solr.common.util.Base64;
 import org.apache.solr.common.util.Utils;
 import org.apache.zookeeper.CreateMode;
 
@@ -72,7 +72,7 @@ public void writeMap(EntryWriter ew) throws IOException {
     }
     ew.put("mode", mode.toString());
     if (data != null) {
-      ew.put("data", Base64.byteArrayToBase64(data));
+      ew.put("data", Base64.getEncoder().encodeToString(data));
     }
   }
 
diff --git a/solr/solrj/src/java/org/apache/solr/client/solrj/impl/Http2SolrClient.java b/solr/solrj/src/java/org/apache/solr/client/solrj/impl/Http2SolrClient.java
index 1543fbe75b1d..72f2af7b1d8d 100644
--- a/solr/solrj/src/java/org/apache/solr/client/solrj/impl/Http2SolrClient.java
+++ b/solr/solrj/src/java/org/apache/solr/client/solrj/impl/Http2SolrClient.java
@@ -27,6 +27,7 @@
 import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
 import java.util.Arrays;
+import java.util.Base64;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Iterator;
@@ -64,7 +65,6 @@
 import org.apache.solr.common.params.ModifiableSolrParams;
 import org.apache.solr.common.params.SolrParams;
 import org.apache.solr.common.params.UpdateParams;
-import org.apache.solr.common.util.Base64;
 import org.apache.solr.common.util.ContentStream;
 import org.apache.solr.common.util.ExecutorUtil;
 import org.apache.solr.common.util.NamedList;
@@ -471,7 +471,7 @@ private ContentType getContentType(Response response) {
   private void setBasicAuthHeader(@SuppressWarnings({"rawtypes"})SolrRequest solrRequest, Request req) {
     if (solrRequest.getBasicAuthUser() != null && solrRequest.getBasicAuthPassword() != null) {
       String userPass = solrRequest.getBasicAuthUser() + ":" + solrRequest.getBasicAuthPassword();
-      String encoded = Base64.byteArrayToBase64(userPass.getBytes(FALLBACK_CHARSET));
+      String encoded = Base64.getEncoder().encodeToString(userPass.getBytes(FALLBACK_CHARSET));
       req.header("Authorization", "Basic " + encoded);
     }
   }
diff --git a/solr/solrj/src/java/org/apache/solr/client/solrj/impl/HttpSolrClient.java b/solr/solrj/src/java/org/apache/solr/client/solrj/impl/HttpSolrClient.java
index e95c5d0d3158..a2af0b6ab200 100644
--- a/solr/solrj/src/java/org/apache/solr/client/solrj/impl/HttpSolrClient.java
+++ b/solr/solrj/src/java/org/apache/solr/client/solrj/impl/HttpSolrClient.java
@@ -29,6 +29,7 @@
 import java.nio.charset.StandardCharsets;
 import java.security.Principal;
 import java.util.Arrays;
+import java.util.Base64;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Iterator;
@@ -79,7 +80,6 @@
 import org.apache.solr.common.params.CommonParams;
 import org.apache.solr.common.params.ModifiableSolrParams;
 import org.apache.solr.common.params.SolrParams;
-import org.apache.solr.common.util.Base64;
 import org.apache.solr.common.util.ContentStream;
 import org.apache.solr.common.util.ExecutorUtil;
 import org.apache.solr.common.util.NamedList;
@@ -276,7 +276,7 @@ private boolean isV2ApiRequest(@SuppressWarnings({"rawtypes"})final SolrRequest
   private void setBasicAuthHeader(@SuppressWarnings({"rawtypes"})SolrRequest request, HttpRequestBase method) throws UnsupportedEncodingException {
     if (request.getBasicAuthUser() != null && request.getBasicAuthPassword() != null) {
       String userPass = request.getBasicAuthUser() + ":" + request.getBasicAuthPassword();
-      String encoded = Base64.byteArrayToBase64(userPass.getBytes(FALLBACK_CHARSET));
+      String encoded = Base64.getEncoder().encodeToString(userPass.getBytes(FALLBACK_CHARSET));
       method.setHeader(new BasicHeader("Authorization", "Basic " + encoded));
     }
   }
diff --git a/solr/solrj/src/java/org/apache/solr/client/solrj/util/ClientUtils.java b/solr/solrj/src/java/org/apache/solr/client/solrj/util/ClientUtils.java
index 887b264306c6..420f432da470 100644
--- a/solr/solrj/src/java/org/apache/solr/client/solrj/util/ClientUtils.java
+++ b/solr/solrj/src/java/org/apache/solr/client/solrj/util/ClientUtils.java
@@ -20,7 +20,9 @@
 import java.io.StringWriter;
 import java.io.Writer;
 import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
+import java.util.Base64;
 import java.util.Collection;
 import java.util.Date;
 import java.util.Map;
@@ -29,7 +31,6 @@
 import org.apache.solr.common.SolrInputDocument;
 import org.apache.solr.common.SolrInputField;
 import org.apache.solr.common.cloud.Slice;
-import org.apache.solr.common.util.Base64;
 import org.apache.solr.common.util.ContentStream;
 import org.apache.solr.common.util.ContentStreamBase;
 import org.apache.solr.common.util.XML;
@@ -111,10 +112,10 @@ private static void writeVal(Writer writer, String name, Object v, String update
       v = ((Date)v).toInstant().toString();
     } else if (v instanceof byte[]) {
       byte[] bytes = (byte[]) v;
-      v = Base64.byteArrayToBase64(bytes, 0, bytes.length);
+      v = Base64.getEncoder().encodeToString(bytes);
     } else if (v instanceof ByteBuffer) {
       ByteBuffer bytes = (ByteBuffer) v;
-      v = Base64.byteArrayToBase64(bytes.array(), bytes.position(),bytes.limit() - bytes.position());
+      v = new String(Base64.getEncoder().encode(bytes).array(), StandardCharsets.ISO_8859_1);
     }
 
     XML.Writable valWriter = null;
diff --git a/solr/solrj/src/java/org/apache/solr/common/util/Base64.java b/solr/solrj/src/java/org/apache/solr/common/util/Base64.java
deleted file mode 100644
index e470ed944958..000000000000
--- a/solr/solrj/src/java/org/apache/solr/common/util/Base64.java
+++ /dev/null
@@ -1,157 +0,0 @@
-/*
- * Licensed to the Apache Software Foundation (ASF) under one or more
- * contributor license agreements.  See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership.
- * The ASF licenses this file to You under the Apache License, Version 2.0
- * (the "License"); you may not use this file except in compliance with
- * the License.  You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package org.apache.solr.common.util;
-
-/**
- * Static methods for translating Base64 encoded strings to byte arrays
- * and vice-versa. 
- */
-
-public class Base64 {
-  /**
-   * This array is a lookup table that translates 6-bit positive integer
-   * index values into their "Base64 Alphabet" equivalents as specified
-   * in Table 1 of RFC 2045.
-   */
-  private static final char intToBase64[] = {
-          'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
-          'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
-          'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
-          'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
-          '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'
-  };
-
-  /**
-   * This array is a lookup table that translates unicode characters
-   * drawn from the "Base64 Alphabet" (as specified in Table 1 of RFC 2045)
-   * into their 6-bit positive integer equivalents.  Characters that
-   * are not in the Base64 alphabet but fall within the bounds of the
-   * array are translated to -1.
-   */
-  private static final byte base64ToInt[] = {
-          -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-          -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-          -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54,
-          55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4,
-          5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
-          24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34,
-          35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51
-  };
-
-  public static String byteArrayToBase64(byte[] a) {
-    return byteArrayToBase64(a, 0, a.length);
-  }
-
-  public static String byteArrayToBase64(byte[] a, int offset, int len) {
-    int aLen = len;
-    int numFullGroups = aLen / 3;
-    int numBytesInPartialGroup = aLen - 3 * numFullGroups;
-    int resultLen = 4 * ((aLen + 2) / 3);
-    StringBuilder result = new StringBuilder(resultLen);
-    char[] intToAlpha = intToBase64;
-
-    // Translate all full groups from byte array elements to Base64
-    int inCursor = offset;
-    for (int i = 0; i < numFullGroups; i++) {
-      int byte0 = a[inCursor++] & 0xff;
-      int byte1 = a[inCursor++] & 0xff;
-      int byte2 = a[inCursor++] & 0xff;
-      result.append(intToAlpha[byte0 >> 2]);
-      result.append(intToAlpha[(byte0 << 4) & 0x3f | (byte1 >> 4)]);
-      result.append(intToAlpha[(byte1 << 2) & 0x3f | (byte2 >> 6)]);
-      result.append(intToAlpha[byte2 & 0x3f]);
-    }
-
-    // Translate partial group if present
-    if (numBytesInPartialGroup != 0) {
-      int byte0 = a[inCursor++] & 0xff;
-      result.append(intToAlpha[byte0 >> 2]);
-      if (numBytesInPartialGroup == 1) {
-        result.append(intToAlpha[(byte0 << 4) & 0x3f]);
-        result.append("==");
-      } else {
-        // assert numBytesInPartialGroup == 2;
-        int byte1 = a[inCursor++] & 0xff;
-        result.append(intToAlpha[(byte0 << 4) & 0x3f | (byte1 >> 4)]);
-        result.append(intToAlpha[(byte1 << 2) & 0x3f]);
-        result.append('=');
-      }
-    }
-    return result.toString();
-  }
-
-  public static byte[] base64ToByteArray(String s) {
-    byte[] alphaToInt = base64ToInt;
-    int sLen = s.length();
-    int numGroups = sLen / 4;
-    if (4 * numGroups != sLen)
-      throw new IllegalArgumentException(
-              "String length must be a multiple of four.");
-    int missingBytesInLastGroup = 0;
-    int numFullGroups = numGroups;
-    if (sLen != 0) {
-      if (s.charAt(sLen - 1) == '=') {
-        missingBytesInLastGroup++;
-        numFullGroups--;
-      }
-      if (s.charAt(sLen - 2) == '=')
-        missingBytesInLastGroup++;
-    }
-    byte[] result = new byte[3 * numGroups - missingBytesInLastGroup];
-
-    // Translate all full groups from base64 to byte array elements
-    int inCursor = 0, outCursor = 0;
-    for (int i = 0; i < numFullGroups; i++) {
-      int ch0 = base64toInt(s.charAt(inCursor++), alphaToInt);
-      int ch1 = base64toInt(s.charAt(inCursor++), alphaToInt);
-      int ch2 = base64toInt(s.charAt(inCursor++), alphaToInt);
-      int ch3 = base64toInt(s.charAt(inCursor++), alphaToInt);
-      result[outCursor++] = (byte) ((ch0 << 2) | (ch1 >> 4));
-      result[outCursor++] = (byte) ((ch1 << 4) | (ch2 >> 2));
-      result[outCursor++] = (byte) ((ch2 << 6) | ch3);
-    }
-
-    // Translate partial group, if present
-    if (missingBytesInLastGroup != 0) {
-      int ch0 = base64toInt(s.charAt(inCursor++), alphaToInt);
-      int ch1 = base64toInt(s.charAt(inCursor++), alphaToInt);
-      result[outCursor++] = (byte) ((ch0 << 2) | (ch1 >> 4));
-
-      if (missingBytesInLastGroup == 1) {
-        int ch2 = base64toInt(s.charAt(inCursor++), alphaToInt);
-        result[outCursor++] = (byte) ((ch1 << 4) | (ch2 >> 2));
-      }
-    }
-    // assert inCursor == s.length()-missingBytesInLastGroup;
-    // assert outCursor == result.length;
-    return result;
-  }
-
-  /**
-   * Translates the specified character, which is assumed to be in the
-   * "Base 64 Alphabet" into its equivalent 6-bit positive integer.
-   *
-   * @throw IllegalArgumentException or ArrayOutOfBoundsException if
-   * c is not in the Base64 Alphabet.
-   */
-  private static int base64toInt(char c, byte[] alphaToInt) {
-    int result = alphaToInt[c];
-    if (result < 0)
-      throw new IllegalArgumentException("Illegal character " + c);
-    return result;
-  }
-}
diff --git a/solr/solrj/src/java/org/apache/solr/common/util/TextWriter.java b/solr/solrj/src/java/org/apache/solr/common/util/TextWriter.java
index f6b2c9e4cd33..eae0dcacbff2 100644
--- a/solr/solrj/src/java/org/apache/solr/common/util/TextWriter.java
+++ b/solr/solrj/src/java/org/apache/solr/common/util/TextWriter.java
@@ -19,8 +19,11 @@
 
 import java.io.IOException;
 import java.io.Writer;
+import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Path;
 import java.util.Arrays;
+import java.util.Base64;
 import java.util.Date;
 import java.util.Iterator;
 import java.util.LinkedHashMap;
@@ -164,7 +167,7 @@ default void writeDate(String name, Date val) throws IOException {
   }
 
   default void writeByteArr(String name, byte[] buf, int offset, int len) throws IOException {
-    writeStr(name, Base64.byteArrayToBase64(buf, offset, len), false);
+    writeStr(name, new String(Base64.getEncoder().encode(ByteBuffer.wrap(buf, offset, len)).array(), StandardCharsets.ISO_8859_1), false);
   }
 
   default void writeInt(String name, int val) throws IOException {
diff --git a/solr/test-framework/src/java/org/apache/solr/cloud/SolrCloudAuthTestCase.java b/solr/test-framework/src/java/org/apache/solr/cloud/SolrCloudAuthTestCase.java
index 462e2abb2100..f9185622bf60 100644
--- a/solr/test-framework/src/java/org/apache/solr/cloud/SolrCloudAuthTestCase.java
+++ b/solr/test-framework/src/java/org/apache/solr/cloud/SolrCloudAuthTestCase.java
@@ -21,6 +21,7 @@
 import java.lang.invoke.MethodHandles;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Base64;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
@@ -40,7 +41,6 @@
 import org.apache.http.message.BasicHeader;
 import org.apache.http.util.EntityUtils;
 import org.apache.solr.client.solrj.embedded.JettySolrRunner;
-import org.apache.solr.common.util.Base64;
 import org.apache.solr.common.util.StrUtils;
 import org.apache.solr.common.util.Utils;
 import org.apache.solr.util.TimeOut;
@@ -239,7 +239,7 @@ private static void verifySecurityStatus(HttpClient cl, String url, String objPa
 
   protected static String makeBasicAuthHeader(String user, String pwd) {
     String userPass = user + ":" + pwd;
-    return "Basic " + Base64.byteArrayToBase64(userPass.getBytes(UTF_8));
+    return "Basic " + Base64.getEncoder().encodeToString(userPass.getBytes(UTF_8));
   }
 
   static String getBearerAuthHeader(JsonWebSignature jws) throws JoseException {