I created DEV environment from fresh install. Once all features are installed, I did TEM --> Manage Admin Data --> Import Admin Data, from the package that I exported from PROD environment. Without realizing key preferences, I just overrided all preferences.
So obviously, I faced FSC error.
Later, I restored preferences by running preference_manager, restoring all site preferences back to original DEV Preference values. Also, deleted all temp folders. Still, am getting this error, while logging into Teamcenter 2 Tier Client.