[Wiggo]

Originally Posted by chaley

Sorry, I forgot the '$' when I replaced my test lookup name with your lookup name. It should be

program: format_date(sublist($#startdates, 0, 1, ','), 'dd MMM yyyy')

It works!

But I get this error message for 'Dezember' - language thing?

calibre, version 7.19.0
FEHLER: Fehlgeschlagen: Unknown string format: 30 Dez 2023

Traceback (most recent call last):
  File "calibre\gui2\dialogs\metadata_bulk.py", line 198, in do_it
  File "calibre\gui2\dialogs\metadata_bulk.py", line 535, in do_all
  File "calibre\db\cache.py", line 85, in call_func_with_lock
  File "calibre\db\cache.py", line 1636, in set_field
  File "calibre\db\write.py", line 568, in set_books
  File "calibre\db\write.py", line 568, in <dictcomp>
  File "calibre\db\write.py", line 73, in adapt_datetime
  File "calibre\utils\date.py", line 114, in parse_date
  File "dateutil\parser\_parser.py", line 1368, in parse
  File "dateutil\parser\_parser.py", line 643, in parse
dateutil.parser._parser.ParserError: Unknown string format: 30 Dez 2023

Edit: Looks loke a language thing. When I switch calibre to English, everything works.