SOLUTION
1.Error while checking framework version for this issue just refresh the login page multiple times. and then try to login. IF issue still persists then try following solution
*) close ERA_server window and go to following path
C:\ERA\metabase\ro you will find the downloads and web folder over their. just rename it as downloads_old and web_old.
and restart the server.
if issue is not solve then generate solar support ticket.