Thank you for your answer. I have asked the hotline. There are too many files that Joplin creates. Web.de limits the number of files allowed per folder to 3000.
Therefore, I ask more questions that arise for me:
Is there a way to limit the number of files?
U. U. I would like to switch to the Joplin cloud, since there will probably not be this problem. But I have two questions: a) Where are the servers located? b) Are they environmentally friendly (renewable energy)?
Not that I know of apart from reducing the number of notes, attachments, tags, etc. But I am not a dev.
According to this post answered by @laurent, the servers are AWS and located in Ohio, but may soon be moved to Europe. I have no idea how environmentally friendly AWS is.
Interesting restriction: I've read somewhere else in this forum that some public clouds have a limit of 100.000 files in total. Has anyone experienced similar issues? Joplin's web clipper (which I like very much) can create a plethora of tiny files if you choose one of the "complete/simplified page" options.