AvroRuntimeException: Not a union: {"type":"long","logicalType":"timestamp-millis"}

I am trying to save the data from Spark dataframe to HDFS using Avro schema stored in the schema registry. However, I get an error while writing the data:

Caused by: org.apache.avro.AvroRuntimeException: Not a union: {"type":"long","logicalType":"timestamp-millis"}
    at org.apache.avro.Schema.getTypes(Schema.java:299)
    at org.apache.spark.sql.avro.AvroSerializer.org$apache$spark$sql$avro$AvroSerializer$$resolveNullableType(AvroSerializer.scala:229)
    at org.apache.spark.sql.avro.AvroSerializer$$anonfun$3.apply(AvroSerializer.scala:209)
    at org.apache.spark.sql.avro.AvroSerializer$$anonfun$3.apply(AvroSerializer.scala:208)
    at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234)
    at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234)
    at scala.collection.immutable.List.foreach(List.scala:392)
    at scala.collection.TraversableLike$class.map(TraversableLike.scala:234)
    at scala.collection.immutable.List.map(List.scala:296)
    at org.apache.spark.sql.avro.AvroSerializer.newStructConverter(AvroSerializer.scala:208)
    at org.apache.spark.sql.avro.AvroSerializer.<init>(AvroSerializer.scala:51)
    at org.apache.spark.sql.avro.AvroOutputWriter.serializer$lzycompute(AvroOutputWriter.scala:42)
    at org.apache.spark.sql.avro.AvroOutputWriter.serializer(AvroOutputWriter.scala:42)
    at org.apache.spark.sql.avro.AvroOutputWriter.write(AvroOutputWriter.scala:64)
    at org.apache.spark.sql.execution.datasources.SingleDirectoryDataWriter.write(FileFormatDataWriter.scala:137)

What could be the reason for it?

The fields in Avro schema look like this:

{"name":"CreateDate","type":["null",{"type":"long","logicalType":"timestamp-millis"}],"default":null}

Here is an example of the date format:

1900-01-01 00:00:00

The data type of this field in Spark dataframe:

|-- CreateDate: timestamp (nullable = true)

This is the way I write the data:

dataDF.write
  .mode("append")
  .format("avro")
  .option(
    "avroSchema",
    SchemaRegistry.getSchema(
      schemaRegistryConfig.url,
      schemaRegistryConfig.dataSchemaSubject,
      schemaRegistryConfig.dataSchemaVersion))
  .save(hdfsURL)