I cannot log out or switch location

A register shift is still open on this device. Close the shift (count cash) before logging out.

This is not a fault. A cash shift belongs to a person on a device, and logging out while it is open would leave money recorded against someone who is no longer there.

The same block applies before switching location, for the same reason: the shift belongs to the location it was opened at.

What to do

Open Cash drawer (or Waiter bank), count the drawer, and close the shift. Then log out.

That is the whole fix in the normal case — a handover is a close and a fresh open, which is what the shift system is designed around.

The person who opened it has gone home

The shift still has to be closed on that device, by someone who may close it. A manager or cashier with the drawer permission can do it.

Count what is actually in the drawer and enter that. Do not guess at what the previous person should have left. The variance is the useful record here — a made-up matching number destroys the only evidence of what happened.

It says I am not allowed

This account cannot open or close the cash drawer on the server.

Your role does not include cash drawer permission. Note that the restaurant owner role cannot open or close a till at all — that is deliberate. Cash handling belongs to cashier and manager logins.

Get someone with the right role to close it. See Roles and what each person can do.

Nobody can get to that device

A device that is lost or broken with a shift open is a manager problem, not a till problem. Revoke the device under Devices so it cannot sign in, and settle the cash against the day close.