Hello, according to Panasonic, error codes beginning with the letter "U" refer to user errors, which can be easily resolved by following the instructions provided in the user manual.
I have also submitted your question to the AI and here is their response:
The U14 error code generally indicates a problem with the steam system (tank not properly engaged, empty, or scaled circuit). To remedy the problem: check the water level, firmly reinsert the tank, empty the recovery tray, or
reset the appliance by unplugging it for 5 to 10 minutes. If the problem persists, the steam circuit may be scaled up, in which case descaling is required.

Hello, I'm sorry, I've never had to fix an error before and therefore can't help you.