I am trying to connect to my mart server and it says Mart version validation failed.
Current ERwin version 9.80.02 is not compatible with Mart version 9.80.00
I checked my erwin version in the Help About and that shows 2019 R1
Your mart server is version 9.8 but your copy of erwin DM is 2019 R1. You can either upgrade your mart server to be 2019 R1 or you can downgrade your copy of erwin DM to r9.8.
Please also see this article which shows how to upgrade your mart server: