Problem solved. It was the OpenTasks app.
SOLUTION: In the permissions settings of the OpenTasks app the option “Contacts” (in german “Kontakte”) has to be turned on.
Thanks for your help.
Hello! I have just installed self-hosted Nextcloud and synchronized its Calendar and Deck through DAVx5 with default calendar and OpenTasks on my android tablet. I got all data from the server to my tablet, but trying to edit a task in OpenTasks gives me this 404 error. Also no more notes are loaded from the server as well as to the server. Can you tell me where could be the problem? Or where to dig?
Username and servername are changed in debug info and no links to calendars.
@rfc2822 Thanks a lot for the quick reply! I thought I had properly searched the forum. Sorry for doubling the topic