@Kishore Sanagapalli

Root Cause: The issue occurs sometimes during the upgrades.

you have to specify the schema of pg_stat_statements and validate the result with below query.

For example: SELECT count(public.pg_stat_statements_reset() ) from public.pg_stat_statements limit 1;

Solution: In-order to fix the issue,

1. We need to validate the relation of existing schemas has relation to public level from the Search_path is pointed to correct schemas or not.

2. Need to check with DBA if pg_stat_statements is enabled in the environment or not. If not, make sure it gets enabled by DBA.

3. Last step: Identify the Operator ID configured in DB to access the application and excute the below query to alter the role

     ALTER ROLE admin SET search_path TO pg_catalog,public,<Schema-Names>,public;

Note: Operator ID is admin in our scenario.

For More Reference: https://www.postgresql.org/docs/11/pgstatstatements.html

Note: The above solution is applied in our environment and the issue has been resolved successfully. The Post will be kept open for any other best solutions and comments.