Migrate to PostgreSQL from H2 - ERROR Set up h2 target database

Hi there! I'm trying to migrate the application DB from h2 to PostgreSQL in my local Metabase instance. Getting the below error.

Earlier we had version 0.42.3, then we upgraded to 0.44.5. When we tried migrating h2 to PostgreSQL, that is when it failed. So started with a new instance and migrated locally, that is also erroring out when migrating.

set MB_DB_TYPE=postgres
set MB_DB_DBNAME=Metabase
set MB_DB_PORT=5432
set MB_DB_USER=xxx
set MB_DB_PASS=yyy
set MB_DB_HOST=localhost
java -jar metabase.jar load-from-h2 metabase.db

Note: a database called "Metabase" is created in the PostgresSQL

Where’s the h2 file located?