dms create replication task SYSTEM ERROR MESSAGE:An internal error

Issue- Can not create a new replication task from either the console or aws cli.

Details
Source - Aws RDS postgres version 10
Target - Aws Redshift cluster with 4 nodes
Both the source and target are in same VPC, there are 5-6 tasks running already which seem to be working fine.
I have tested the endpoint connection for the new task beforehand, it shows successful.

Errors:
Console error : SYSTEM ERROR MESSAGE:An internal error has occurred. Please try your query again at a later time.
aws cli --debug error:
2021-01-13 00:26:00,174 - MainThread - botocore.parsers - DEBUG - Response headers: {'x-amzn-RequestId': '0975d842-34b5-455f-be83-f2aed1f301a0', 'Content-Type': 'application/x-amz-json-1.1', 'Content-Length': '117', 'Date': 'Tue, 12 Jan 2021 18:55:59 GMT', 'Connection': 'close'}
2021-01-13 00:26:00,174 - MainThread - botocore.parsers - DEBUG - Response body:
b'{"__type":"InternalFailure","message":"An internal error has occurred. Please try your query again at a later time."}'

This error message is completely opaque can not figure out where to look. Please help.

Thanks