Issue is happening when the JWT token length is huge due to the huge list of access permissions assigned to the user. (huge HTTP request header size)
Release : 4.9
Component : CA Test Data Manager
Review this documentation link:
https://techdocs.broadcom.com/content/broadcom/techdocs/us/en/ca-enterprise-software/devops/test-data-management/4-9/administrating/ca-tdm-portal-administration/ca-tdm-portal-troubleshooting.html#concept.dita_9470b0b4a38c9e4ddddc8fdd6f7dce6b4e7c1843_tablesize
Set the "maxHttpHeaderSize" attribute in the Tomcat server.xml to a value of "3000000" (include quotes) and restart the service.
This resolved the issue.