ModuleNotFoundError: No module named 'werkzeug.contrib' (erpnext 12.4.3)

[MartinHBramwell]

So I did . . .

cd ${HOME/}frappe-bench
./env/bin/pip install werkzeug==0.16.0

. . . and rebooted the server.

Everything now back to normal.

(but 4 hours of my life down the toilet)