Deserialization error when using an evolved schema

Schema Registry
1

I originally had the following schema

{
"type":"record",
"name":"EntityA",
"fields":[
  {"name":"values",
   "type": {"type":"array","items": {"type":"record","name":"SubEntities",
     "fields":[
      {"name":"name","type":"string"}, 
      {"name":"valueMap", "type":["null",{"type":"map","values":"string"}], "default":null}
      ]
   }}
  }
 ]
}

I had stored records serialized using this schema in rocksdb, then I added another field to this schema

{
"type":"record",
"name":"EntityA",
"fields":[
  {"name":"values",
   "type": {"type":"array","items": {"type":"record","name":"SubEntities",
     "fields":[
      {"name":"name","type":"string"}, 
      {"name":"valueMap", "type":["null",{"type":"map","values":"string"}], "default":null},
      {"name":"newMap", "type":["null",{"type":"map","values":"int"}], "default":null},
      ]
   }}
  }
 ]
}

Now I am using this above schema but also have the original schema registered with schema-registry. Suddenly, I start getting this error.

org.apache.kafka.common.errors.SerializationException: Error deserializing Avro message for id 5
Caused by: java.lang.ArrayIndexOutOfBoundsException: Index 27 out of bounds for length 2
at org.apache.avro.io.parsing.Symbol$Alternative.getSymbol(Symbol.java:460)
at org.apache.avro.io.ResolvingDecoder.readIndex(ResolvingDecoder.java:283)
at org.apache.avro.generic.GenericDatumReader.readWithoutConversion(GenericDatumReader.java:188)
at org.apache.avro.specific.SpecificDatumReader.readField(SpecificDatumReader.java:136)
at org.apache.avro.generic.GenericDatumReader.readRecord(GenericDatumReader.java:248)
at org.apache.avro.specific.SpecificDatumReader.readRecord(SpecificDatumReader.java:123)
at org.apache.avro.generic.GenericDatumReader.readWithoutConversion(GenericDatumReader.java:180)
at org.apache.avro.generic.GenericDatumReader.readArray(GenericDatumReader.java:299)
at org.apache.avro.generic.GenericDatumReader.readWithoutConversion(GenericDatumReader.java:184)
at org.apache.avro.specific.SpecificDatumReader.readField(SpecificDatumReader.java:136)
at org.apache.avro.generic.GenericDatumReader.readRecord(GenericDatumReader.java:248)
at org.apache.avro.specific.SpecificDatumReader.readRecord(SpecificDatumReader.java:123)
at org.apache.avro.generic.GenericDatumReader.readWithoutConversion(GenericDatumReader.java:180)
at org.apache.avro.generic.GenericDatumReader.read(GenericDatumReader.java:161)
at org.apache.avro.generic.GenericDatumReader.read(GenericDatumReader.java:154)

where id 5 corresponds to the original schema above. Can someone please help to understand the reason for this error.