diff --git a/sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/bigquery/AvroGenericRecordToStorageApiProto.java b/sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/bigquery/AvroGenericRecordToStorageApiProto.java
index c721395eec79..856c29b0c535 100644
--- a/sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/bigquery/AvroGenericRecordToStorageApiProto.java
+++ b/sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/bigquery/AvroGenericRecordToStorageApiProto.java
@@ -86,7 +86,7 @@ public class AvroGenericRecordToStorageApiProto {
           .put(Schema.Type.STRING, Object::toString)
           .put(Schema.Type.BOOLEAN, Function.identity())
           .put(Schema.Type.ENUM, o -> o.toString())
-          .put(Schema.Type.BYTES, o -> ByteString.copyFrom(((ByteBuffer) o).duplicate()))
+          .put(Schema.Type.BYTES, AvroGenericRecordToStorageApiProto::convertBytes)
           .build();
 
   // A map of supported logical types to their encoding functions.
@@ -145,6 +145,16 @@ static ByteString convertDecimal(LogicalType logicalType, Object value) {
     return BeamRowToStorageApiProto.serializeBigDecimalToNumeric(bigDecimal);
   }
 
+  static ByteString convertBytes(Object value) {
+    if (value instanceof byte[]) {
+      // for backward compatibility
+      // this is not accepted by the avro spec, but users may have abused it
+      return ByteString.copyFrom((byte[]) value);
+    } else {
+      return ByteString.copyFrom(((ByteBuffer) value).duplicate());
+    }
+  }
+
   /**
    * Given an Avro Schema, returns a protocol-buffer TableSchema that can be used to write data
    * through BigQuery Storage API.
diff --git a/sdks/java/io/google-cloud-platform/src/test/java/org/apache/beam/sdk/io/gcp/bigquery/AvroGenericRecordToStorageApiProtoTest.java b/sdks/java/io/google-cloud-platform/src/test/java/org/apache/beam/sdk/io/gcp/bigquery/AvroGenericRecordToStorageApiProtoTest.java
index 472173c67412..c073dec4752d 100644
--- a/sdks/java/io/google-cloud-platform/src/test/java/org/apache/beam/sdk/io/gcp/bigquery/AvroGenericRecordToStorageApiProtoTest.java
+++ b/sdks/java/io/google-cloud-platform/src/test/java/org/apache/beam/sdk/io/gcp/bigquery/AvroGenericRecordToStorageApiProtoTest.java
@@ -77,6 +77,7 @@ enum TestEnum {
       SchemaBuilder.record("TestRecord")
           .fields()
           .optionalBytes("bytesValue")
+          .optionalBytes("byteBufferValue")
           .requiredInt("intValue")
           .optionalLong("longValue")
           .optionalFloat("floatValue")
@@ -138,64 +139,71 @@ enum TestEnum {
                   .build())
           .addField(
               FieldDescriptorProto.newBuilder()
-                  .setName("intvalue")
+                  .setName("bytebuffervalue")
                   .setNumber(2)
+                  .setType(Type.TYPE_BYTES)
+                  .setLabel(Label.LABEL_OPTIONAL)
+                  .build())
+          .addField(
+              FieldDescriptorProto.newBuilder()
+                  .setName("intvalue")
+                  .setNumber(3)
                   .setType(Type.TYPE_INT64)
                   .setLabel(Label.LABEL_OPTIONAL)
                   .build())
           .addField(
               FieldDescriptorProto.newBuilder()
                   .setName("longvalue")
-                  .setNumber(3)
+                  .setNumber(4)
                   .setType(Type.TYPE_INT64)
                   .setLabel(Label.LABEL_OPTIONAL)
                   .build())
           .addField(
               FieldDescriptorProto.newBuilder()
                   .setName("floatvalue")
-                  .setNumber(4)
+                  .setNumber(5)
                   .setType(Type.TYPE_DOUBLE)
                   .setLabel(Label.LABEL_OPTIONAL)
                   .build())
           .addField(
               FieldDescriptorProto.newBuilder()
                   .setName("doublevalue")
-                  .setNumber(5)
+                  .setNumber(6)
                   .setType(Type.TYPE_DOUBLE)
                   .setLabel(Label.LABEL_OPTIONAL)
                   .build())
           .addField(
               FieldDescriptorProto.newBuilder()
                   .setName("stringvalue")
-                  .setNumber(6)
+                  .setNumber(7)
                   .setType(Type.TYPE_STRING)
                   .setLabel(Label.LABEL_OPTIONAL)
                   .build())
           .addField(
               FieldDescriptorProto.newBuilder()
                   .setName("booleanvalue")
-                  .setNumber(7)
+                  .setNumber(8)
                   .setType(Type.TYPE_BOOL)
                   .setLabel(Label.LABEL_OPTIONAL)
                   .build())
           .addField(
               FieldDescriptorProto.newBuilder()
                   .setName("arrayvalue")
-                  .setNumber(8)
+                  .setNumber(9)
                   .setType(Type.TYPE_STRING)
                   .setLabel(Label.LABEL_REPEATED)
                   .build())
           .addField(
               FieldDescriptorProto.newBuilder()
                   .setName("enumvalue")
-                  .setNumber(9)
+                  .setNumber(10)
                   .setType(Type.TYPE_STRING)
                   .setLabel(Label.LABEL_OPTIONAL)
                   .build())
           .addField(
               FieldDescriptorProto.newBuilder()
                   .setName("fixedvalue")
-                  .setNumber(10)
+                  .setNumber(11)
                   .setType(Type.TYPE_BYTES)
                   .setLabel(Label.LABEL_REQUIRED)
                   .build())
@@ -309,7 +317,8 @@ enum TestEnum {
       Instant now = Instant.now();
       baseRecord =
           new GenericRecordBuilder(BASE_SCHEMA)
-              .set("bytesValue", ByteBuffer.wrap(BYTES))
+              .set("bytesValue", BYTES)
+              .set("byteBufferValue", ByteBuffer.wrap(BYTES))
               .set("intValue", (int) 3)
               .set("longValue", (long) 4)
               .set("floatValue", (float) 3.14)
@@ -346,6 +355,7 @@ enum TestEnum {
       baseProtoExpectedFields =
           ImmutableMap.<String, Object>builder()
               .put("bytesvalue", ByteString.copyFrom(BYTES))
+              .put("bytebuffervalue", ByteString.copyFrom(BYTES))
               .put("intvalue", (long) 3)
               .put("longvalue", (long) 4)
               .put("floatvalue", (double) 3.14)