Just entering the admin_update.php (first time since Tuesday last week) WARNING: Could not find execute 'git fetch'.
Error details:- error: insufficient permission for adding an object to repository database .git/objects fatal: failed to write object fatal: unpack-objects failed
Things to check: Is Git installed? Is the Git origin/remote correct? Are web server file permissions too strict?
Seek support on the Forum if required - include relevant PHP error logs & ITFlow debug output
Most of the permissions for the directories under .git/objects were root:root - changed to www-data:www-data and the error message changed to another folder under .git/.
Not sure what happened, but I ended up resetting the owner on .git to www-data:www-data.
Just a heads up in case anyone else has this issue.