[Midge]

The following error pops up:

calibre, version 8.3.0
ERROR: Failed: Failed to export data. Click "Show details" for more information.

Traceback (most recent call last):
File "calibre\gui2\dialogs\exim.py", line 156, in run_action
File "calibre\utils\exim.py", line 213, in export
File "calibre\db\cache.py", line 85, in call_func_with_lock
File "calibre\db\cache.py", line 3179, in export_library
File "calibre\db\cache.py", line 1233, in copy_format_to
File "calibre\db\backend.py", line 1856, in copy_format_to
File "shutil.py", line 197, in copyfileobj
OSError: [Errno 22] Invalid argument

Apologies if the answer is obvious. I'm a bit thick.