Default file name contains illegal characters

[dschwerdel]

The default filename is created from the date + local time format (I guess)

So my suggested filenames are eg. OpenScan 2025-05-14 19:34:44.3415...

Could you by default sanitize the filenames? There's no issue saving the file as pdf on my device.

But when I export the file to nexcloud there's an error.

I suggest you stay in the posix character set https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_282