thanks for the answer! changed the password through pgadmin, problem persists. i believe the problem is with the username that is in use, above mentioned error refers 'openpg' username while my postgresql db is using 'postgres' username. can this be the root cause? else plz suggest. thank you!

During the time of installation did you change username,password?

tried re-installing postresql thrice, everytime it was showing superuser as 'postgres'. ideally what should be the username/password at different stages of postgresql installation?

In windows the default user is openpg & default password is openpgpwd.