Export failes everytime

In Lightroom (desktop version) I edit pictures that I took with my mobile phone (Samsung Galaxy S21). Lately I've been getting an error message every time I try to export the edited images. Lightroom downloads them to the end and then aborts at the end (Some exports encountered errors or displayed warnings. The file could not be created). I haven't made any changes, so I can't explain why it suddenly stopped working. Does anyone of you know where the problem could lie?

 I would be very grateful for help,

Anne