Se ha producido un error interno: ?:0: attempt to index a nil value

Please post your System Information as Lightroom Classic (LrC) reports it. In LrC click on Help, then System Info, then Copy. Paste that information into a reply. Please present all information from first line down to and including Plug-in Info. Info after Plug-in info can be cut as that is just so much dead space to us non-Techs.

It seems that your catalog file has a fault or there's a problem with an plugin.

More informations you'll find here:

A corrupt catalog causes an error message saying "attempt to index a nil value" (lightroom-plugins.com)

Gelöst: Ein interner Fehler ist aufgetreten: ?:0: attempt ... - Adobe Support Community - 9851754

Gelöst: an internal error occurred: ?:0: attempt to index ... - Adobe Support Community - 9782623