Changing from master to staging branch: Error cannot import name Database

I Fixed it.

If you are shifting between branches and facing this error (I face this error when I switch to develop and then back to staging-fixes), run the following command

if you are in frappe-bench folder

frappe-bench > cd apps/frappe
frappe-bench/apps/frappe > find . -name “*.pyc” -exec rm -f {} ;

Then
bench build & migrate. Working fine.