Are you facing this error on v15?

OperationalError

pymysql.err.OperationalError: (1054, “Unknown column ‘default_app’ in ‘field list’”)

migrate the site and bench build --force. check it.

No, I am not facing this error.

Kindly check whether you have installed any custom app on your site ?

If there is any custom app installed on your site, remove that and migrate the site.

I think this may help you.

Yes Solved this using command bench migrate
Thank you both!