diff --git a/connectors/cache/fallback_test.go b/connectors/cache/fallback_test.go
index 6ca1b862..f9a42b85 100644
--- a/connectors/cache/fallback_test.go
+++ b/connectors/cache/fallback_test.go
@@ -273,7 +273,7 @@ func createReadNotFoundTestCase() testCase {
 		encoder:        NewJSONEncoder(),
 		cachedEntities: cacheableEntities,
 		originRead: &expectArgs{
-			err: originErr,
+			err:  originErr,
 			resp: originResponse,
 		},
 		expectedResp: originResponse,
diff --git a/connectors/routing/connector.go b/connectors/routing/connector.go
index 54b3360e..2e44c999 100644
--- a/connectors/routing/connector.go
+++ b/connectors/routing/connector.go
@@ -183,7 +183,7 @@ func (rc *Connector) Scan(ctx context.Context, ei *dosa.EntityInfo, minimumField
 func (rc *Connector) CheckSchema(ctx context.Context, scope, namePrefix string, ed []*dosa.EntityDefinition) (int32, error) {
 	connector, err := rc.getConnector(scope, namePrefix, "CheckSchema")
 	if err != nil {
-		return dosa.InvalidVersion, base.ErrNoMoreConnector{}
+		return dosa.InvalidVersion, err
 	}
 	return connector.CheckSchema(ctx, scope, namePrefix, ed)
 }
@@ -192,7 +192,7 @@ func (rc *Connector) CheckSchema(ctx context.Context, scope, namePrefix string,
 func (rc *Connector) UpsertSchema(ctx context.Context, scope, namePrefix string, ed []*dosa.EntityDefinition) (*dosa.SchemaStatus, error) {
 	connector, err := rc.getConnector(scope, namePrefix, "UpsertSchema")
 	if err != nil {
-		return nil, base.ErrNoMoreConnector{}
+		return nil, err
 	}
 	return connector.UpsertSchema(ctx, scope, namePrefix, ed)
 }
@@ -201,7 +201,7 @@ func (rc *Connector) UpsertSchema(ctx context.Context, scope, namePrefix string,
 func (rc *Connector) CheckSchemaStatus(ctx context.Context, scope string, namePrefix string, version int32) (*dosa.SchemaStatus, error) {
 	connector, err := rc.getConnector(scope, namePrefix, "CheckSchemaStatus")
 	if err != nil {
-		return nil, base.ErrNoMoreConnector{}
+		return nil, err
 	}
 	return connector.CheckSchemaStatus(ctx, scope, namePrefix, version)
 }
@@ -211,7 +211,7 @@ func (rc *Connector) CreateScope(ctx context.Context, scope string) error {
 	// will fall to default connector
 	connector, err := rc.getConnector(scope, "", "CreateScope")
 	if err != nil {
-		return base.ErrNoMoreConnector{}
+		return err
 	}
 	return connector.CreateScope(ctx, scope)
 }
@@ -221,7 +221,7 @@ func (rc *Connector) TruncateScope(ctx context.Context, scope string) error {
 	// will fall to default connector
 	connector, err := rc.getConnector(scope, "", "TruncateScope")
 	if err != nil {
-		return base.ErrNoMoreConnector{}
+		return err
 	}
 	return connector.TruncateScope(ctx, scope)
 }
@@ -231,7 +231,7 @@ func (rc *Connector) DropScope(ctx context.Context, scope string) error {
 	// will fall to default connector
 	connector, err := rc.getConnector(scope, "", "DropScope")
 	if err != nil {
-		return base.ErrNoMoreConnector{}
+		return err
 	}
 	return connector.DropScope(ctx, scope)
 }
@@ -241,7 +241,7 @@ func (rc *Connector) ScopeExists(ctx context.Context, scope string) (bool, error
 	// will fall to default connector
 	connector, err := rc.getConnector(scope, "", "ScopeExists")
 	if err != nil {
-		return false, base.ErrNoMoreConnector{}
+		return false, err
 	}
 	return connector.ScopeExists(ctx, scope)
 }
diff --git a/connectors/yarpc/yarpc.go b/connectors/yarpc/yarpc.go
index 0bcbbffc..065951c5 100644
--- a/connectors/yarpc/yarpc.go
+++ b/connectors/yarpc/yarpc.go
@@ -228,8 +228,12 @@ func (c *Connector) CreateIfNotExists(ctx context.Context, ei *dosa.EntityInfo,
 				return errors.Wrap(&dosa.ErrAlreadyExists{}, "failed to create")
 			}
 		}
+
+		if !dosarpc.Dosa_CreateIfNotExists_Helper.IsException(err) {
+			return errors.Wrap(err, "failed to CreateIfNotExists due to network issue")
+		}
 	}
-	return errors.Wrap(err, "failed to create")
+	return errors.Wrap(err, "failed to CreateIfNotExists")
 }
 
 // Upsert inserts or updates your data
@@ -242,7 +246,14 @@ func (c *Connector) Upsert(ctx context.Context, ei *dosa.EntityInfo, values map[
 		Ref:          entityInfoToSchemaRef(ei),
 		EntityValues: ev,
 	}
-	return c.Client.Upsert(ctx, &upsertRequest, VersionHeader())
+
+	err = c.Client.Upsert(ctx, &upsertRequest, VersionHeader())
+
+	if !dosarpc.Dosa_Upsert_Helper.IsException(err) {
+		return errors.Wrap(err, "failed to Upsert due to network issue")
+	}
+
+	return errors.Wrap(err, "failed to Upsert")
 }
 
 // Read reads a single entity
@@ -284,7 +295,12 @@ func (c *Connector) Read(ctx context.Context, ei *dosa.EntityInfo, keys map[stri
 				return nil, errors.Wrap(&dosa.ErrNotFound{}, "Read failed: not found")
 			}
 		}
-		return nil, errors.Wrap(err, "Read failed")
+
+		if !dosarpc.Dosa_Read_Helper.IsException(err) {
+			return nil, errors.Wrap(err, "failed to Read due to network issue")
+		}
+
+		return nil, errors.Wrap(err, "failed to Read")
 	}
 
 	// no error, so for each column, transform it into the map of (col->value) items
@@ -323,7 +339,11 @@ func (c *Connector) MultiRead(ctx context.Context, ei *dosa.EntityInfo, keys []m
 
 	response, err := c.Client.MultiRead(ctx, request, VersionHeader())
 	if err != nil {
-		return nil, errors.Wrap(err, "MultiRead failed")
+		if !dosarpc.Dosa_MultiRead_Helper.IsException(err) {
+			return nil, errors.Wrap(err, "failed to MultiRead due to network issue")
+		}
+
+		return nil, errors.Wrap(err, "failed to MultiRead")
 	}
 
 	rpcResults := response.Results
@@ -376,7 +396,11 @@ func (c *Connector) Remove(ctx context.Context, ei *dosa.EntityInfo, keys map[st
 
 	err := c.Client.Remove(ctx, removeRequest, VersionHeader())
 	if err != nil {
-		return errors.Wrap(err, "Remove failed")
+		if !dosarpc.Dosa_Remove_Helper.IsException(err) {
+			return errors.Wrap(err, "failed to Remove due to network issue")
+		}
+
+		return errors.Wrap(err, "failed to Remove")
 	}
 	return nil
 }
@@ -394,7 +418,10 @@ func (c *Connector) RemoveRange(ctx context.Context, ei *dosa.EntityInfo, column
 	}
 
 	if err := c.Client.RemoveRange(ctx, request, VersionHeader()); err != nil {
-		return errors.Wrap(err, "RemoveRange failed")
+		if !dosarpc.Dosa_RemoveRange_Helper.IsException(err) {
+			return errors.Wrap(err, "failed to RemoveRange due to network issue")
+		}
+		return errors.Wrap(err, "failed to RemoveRange")
 	}
 	return nil
 }
@@ -410,7 +437,7 @@ func (c *Connector) Range(ctx context.Context, ei *dosa.EntityInfo, columnCondit
 	rpcMinimumFields := makeRPCminimumFields(minimumFields)
 	rpcConditions, err := createRPCConditions(columnConditions)
 	if err != nil {
-		return nil, "", errors.Wrap(err, "Range failed: invalid column conditions")
+		return nil, "", errors.Wrap(err, "failed to Range: invalid column conditions")
 	}
 	rangeRequest := dosarpc.RangeRequest{
 		Ref:          entityInfoToSchemaRef(ei),
@@ -421,7 +448,11 @@ func (c *Connector) Range(ctx context.Context, ei *dosa.EntityInfo, columnCondit
 	}
 	response, err := c.Client.Range(ctx, &rangeRequest, VersionHeader())
 	if err != nil {
-		return nil, "", errors.Wrap(err, "Range failed")
+		if !dosarpc.Dosa_Range_Helper.IsException(err) {
+			return nil, "", errors.Wrap(err, "failed to Range due to network issue")
+		}
+
+		return nil, "", errors.Wrap(err, "failed to Range")
 	}
 	results := []map[string]dosa.FieldValue{}
 	for _, entity := range response.Entities {
@@ -466,7 +497,11 @@ func (c *Connector) Scan(ctx context.Context, ei *dosa.EntityInfo, minimumFields
 	}
 	response, err := c.Client.Scan(ctx, &scanRequest, VersionHeader())
 	if err != nil {
-		return nil, "", errors.Wrap(err, "Scan failed")
+		if !dosarpc.Dosa_Scan_Helper.IsException(err) {
+			return nil, "", errors.Wrap(err, "failed to Scan due to network issue")
+		}
+
+		return nil, "", errors.Wrap(err, "failed to Scan")
 	}
 	results := []map[string]dosa.FieldValue{}
 	for _, entity := range response.Entities {
@@ -487,7 +522,11 @@ func (c *Connector) CheckSchema(ctx context.Context, scope, namePrefix string, e
 	}
 	response, err := c.Client.CheckSchema(ctx, &csr, VersionHeader())
 	if err != nil {
-		return dosa.InvalidVersion, wrapError(err, "CheckSchema failed", scope, c.Config.ServiceName)
+		if !dosarpc.Dosa_CheckSchema_Helper.IsException(err) {
+			return dosa.InvalidVersion, errors.Wrap(err, "failed to CheckSchema due to network issue")
+		}
+
+		return dosa.InvalidVersion, wrapError(err, "failed to CheckSchema", scope, c.Config.ServiceName)
 	}
 
 	return *response.Version, nil
@@ -506,7 +545,10 @@ func (c *Connector) CanUpsertSchema(ctx context.Context, scope, namePrefix strin
 	}
 	response, err := c.Client.CanUpsertSchema(ctx, &csr, VersionHeader())
 	if err != nil {
-		return dosa.InvalidVersion, wrapError(err, "Check schema compatibility failed", scope, c.Config.ServiceName)
+		if !dosarpc.Dosa_CanUpsertSchema_Helper.IsException(err) {
+			return dosa.InvalidVersion, errors.Wrap(err, "failed to CanUpsertSchema due to network issue")
+		}
+		return dosa.InvalidVersion, wrapError(err, "failed to CanUpsertSchema", scope, c.Config.ServiceName)
 	}
 
 	return *response.Version, nil
@@ -523,7 +565,10 @@ func (c *Connector) UpsertSchema(ctx context.Context, scope, namePrefix string,
 
 	response, err := c.Client.UpsertSchema(ctx, request, VersionHeader())
 	if err != nil {
-		return nil, wrapError(err, "UpsertSchema failed", scope, c.Config.ServiceName)
+		if !dosarpc.Dosa_UpsertSchema_Helper.IsException(err) {
+			return nil, errors.Wrap(err, "failed to UpsertSchema due to network issue")
+		}
+		return nil, wrapError(err, "failed to UpsertSchema", scope, c.Config.ServiceName)
 	}
 
 	status := ""
@@ -532,7 +577,7 @@ func (c *Connector) UpsertSchema(ctx context.Context, scope, namePrefix string,
 	}
 
 	if response.Version == nil {
-		return nil, errors.New("UpsertSchema failed: server returns version nil")
+		return nil, errors.New("failed to UpsertSchema: server returns version nil")
 	}
 
 	return &dosa.SchemaStatus{
@@ -547,7 +592,11 @@ func (c *Connector) CheckSchemaStatus(ctx context.Context, scope, namePrefix str
 	response, err := c.Client.CheckSchemaStatus(ctx, &request, VersionHeader())
 
 	if err != nil {
-		return nil, wrapError(err, "ChecksShemaStatus failed", scope, c.Config.ServiceName)
+		if !dosarpc.Dosa_CheckSchemaStatus_Helper.IsException(err) {
+			return nil, errors.Wrap(err, "failed to CheckSchemaStatus due to network issue")
+		}
+
+		return nil, wrapError(err, "failed to CheckSchemaStatus", scope, c.Config.ServiceName)
 	}
 
 	status := ""
@@ -556,7 +605,7 @@ func (c *Connector) CheckSchemaStatus(ctx context.Context, scope, namePrefix str
 	}
 
 	if response.Version == nil {
-		return nil, errors.New("ChecksShemaStatus failed: server returns version nil")
+		return nil, errors.New("failed to ChecksShemaStatus: server returns version nil")
 	}
 
 	return &dosa.SchemaStatus{
@@ -572,7 +621,11 @@ func (c *Connector) CreateScope(ctx context.Context, scope string) error {
 	}
 
 	if err := c.Client.CreateScope(ctx, request, VersionHeader()); err != nil {
-		return errors.Wrap(err, "CreateScope failed")
+		if !dosarpc.Dosa_CreateScope_Helper.IsException(err) {
+			return errors.Wrap(err, "failed to CreateScope due to network issue")
+		}
+
+		return errors.Wrap(err, "failed to CreateScope")
 	}
 
 	return nil
@@ -585,7 +638,11 @@ func (c *Connector) TruncateScope(ctx context.Context, scope string) error {
 	}
 
 	if err := c.Client.TruncateScope(ctx, request, VersionHeader()); err != nil {
-		return errors.Wrap(err, "TruncateScope failed")
+		if !dosarpc.Dosa_TruncateScope_Helper.IsException(err) {
+			return errors.Wrap(err, "failed to TruncateScope due to network issue")
+		}
+
+		return errors.Wrap(err, "failed to TruncateScope")
 	}
 
 	return nil
@@ -598,7 +655,11 @@ func (c *Connector) DropScope(ctx context.Context, scope string) error {
 	}
 
 	if err := c.Client.DropScope(ctx, request, VersionHeader()); err != nil {
-		return errors.Wrap(err, "DropScope failed")
+		if !dosarpc.Dosa_DropScope_Helper.IsException(err) {
+			return errors.Wrap(err, "failed to DropScope due to network issue")
+		}
+
+		return errors.Wrap(err, "failed to DropScope")
 	}
 
 	return nil
diff --git a/entity_parser.go b/entity_parser.go
index 975ac3db..20a712de 100644
--- a/entity_parser.go
+++ b/entity_parser.go
@@ -100,6 +100,10 @@ func parsePartitionKey(pkStr string) []string {
 
 // parsePrimaryKey func parses the primary key of DOSA object
 func parsePrimaryKey(tableName, pkStr string) (*PrimaryKey, error) {
+	// parens must be matched
+	if !parensBalanced(pkStr) {
+		return nil, fmt.Errorf("unmatched parentheses: %q", pkStr)
+	}
 	// filter out "trailing comma and space"
 	pkStr = strings.TrimRight(pkStr, ", ")
 	pkStr = strings.TrimSpace(pkStr)
@@ -384,6 +388,26 @@ func parseField(typ Type, isPointer bool, name string, tag string) (*ColumnDefin
 	return &ColumnDefinition{Name: name, IsPointer: isPointer, Type: typ}, nil
 }
 
+func parensBalanced(s string) bool {
+	// This is effectively pushing left parens on the stack, and popping them when
+	// a right paren is seen. Since the stack only ever contains the same character,
+	// we don't actually need the stack -- only its size.
+	var ssize uint
+	for i := 0; i < len(s); i++ {
+		if s[i] == '(' {
+			ssize++
+		} else if s[i] == ')' {
+			if ssize == 0 {
+				// Extra right paren
+				return false
+			}
+			ssize--
+		}
+	}
+	// Stack must be empty
+	return ssize == 0
+}
+
 var (
 	uuidType       = reflect.TypeOf(UUID(""))
 	blobType       = reflect.TypeOf([]byte{})
diff --git a/entity_parser_test.go b/entity_parser_test.go
index 0effd9af..9f3f562e 100644
--- a/entity_parser_test.go
+++ b/entity_parser_test.go
@@ -492,6 +492,35 @@ func TestInvalidFieldInTag(t *testing.T) {
 	assert.Contains(t, err.Error(), "invalid")
 }
 
+func TestInvalidSyntaxInTag(t *testing.T) {
+	type HasInvalidTagSyntax struct {
+		Entity `dosa:"primaryKey=((Val, Key), TS DESC"`
+		Val    string
+		Key    string
+		TS     time.Time
+	}
+	table, err := TableFromInstance(&HasInvalidTagSyntax{})
+	assert.Nil(t, table)
+	assert.Error(t, err)
+	assert.Contains(t, err.Error(), "unmatched parentheses")
+}
+
+func TestParensBalanced(t *testing.T) {
+	assert.True(t, parensBalanced("()"))
+	assert.True(t, parensBalanced("()()"))
+	assert.True(t, parensBalanced("(()())"))
+	assert.True(t, parensBalanced("()"))
+	assert.True(t, parensBalanced(""))
+	assert.True(t, parensBalanced("()(()(()(()()))())()()"))
+
+	assert.False(t, parensBalanced("("))
+	assert.False(t, parensBalanced(")"))
+	assert.False(t, parensBalanced("(()"))
+	assert.False(t, parensBalanced(")("))
+	assert.False(t, parensBalanced("(()))"))
+	assert.False(t, parensBalanced("((()())"))
+}
+
 /*
  These tests do not currently pass, but I think they should
 */
diff --git a/finder_test.go b/finder_test.go
index 76a9e42b..60d66fae 100644
--- a/finder_test.go
+++ b/finder_test.go
@@ -80,7 +80,7 @@ func TestParser(t *testing.T) {
 
 	assert.Equal(t, len(expectedEntities)+len(entitiesExcludedForTest), len(entities), fmt.Sprintf("%s", entities))
 	// TODO(jzhan): remove the hard-coded number of errors.
-	assert.Equal(t, 21, len(errs), fmt.Sprintf("%v", errs))
+	assert.Equal(t, 22, len(errs), fmt.Sprintf("%v", errs))
 	assert.Nil(t, err)
 
 	for _, entity := range entities {
diff --git a/mocks/client.go b/mocks/client.go
index 3bd25f2e..55e3f2f5 100644
--- a/mocks/client.go
+++ b/mocks/client.go
@@ -26,9 +26,10 @@ package mocks
 
 import (
 	context "context"
+	reflect "reflect"
+
 	gomock "github.com/golang/mock/gomock"
 	dosa "github.com/uber-go/dosa"
-	reflect "reflect"
 )
 
 // MockClient is a mock of Client interface
diff --git a/mocks/connector.go b/mocks/connector.go
index b873228e..f1ee7e00 100644
--- a/mocks/connector.go
+++ b/mocks/connector.go
@@ -26,9 +26,10 @@ package mocks
 
 import (
 	context "context"
+	reflect "reflect"
+
 	gomock "github.com/golang/mock/gomock"
 	dosa "github.com/uber-go/dosa"
-	reflect "reflect"
 )
 
 // MockConnector is a mock of Connector interface