MongoDB :Auth mechanism not specified Error for specific Project

We running 2 web .net project on same Pc and connecting to same Mongod server . first and second project connect to same database.

First project with authorization connection string working fine without connection issue but Second project with same authorization string giving Auth mechanism not specified error if I specified any auth mechanism then it giving Unsupported MongoAuthenticationMechanism SCRAM-SHA-1 error

This is happen only for second project , not issue with first project I am sure that

1. both mongod server and shell version match
2. same connection string for both

but why it giving issue for second project only. what would be possible project level issue? any idea.

Please help for this