Upload impossible: "cannot authentificate over ajax calls"

I have upgraded from debian 9 to debian 10 (buster). And from nextcloud 13 to 17.0.1.
Now the upload of files is impossible.
I have installed a new installation: No problems with upload:
Therefore this is not a problem of the php environment or NGINX configuration (same configuration excluding root, server name, logs and certificate)
Any ideas?

How did you upgrade Nextcloud? Through each major version? NC 13 -> 14 -> 15 -> 16 -> 17?
What do the logs say?

Al right: NC 13 -> 14 -> 15 -> 16 -> 17
No errors in log. The error message comes from the client (jscript).

if (!$this->userSession->isLoggedIn() && in_array('XMLHttpRequest', explode(',', $request->getHeader('X-Requested-With')))) { // do not re-authenticate over ajax, use dummy auth name to prevent browser popup $response->addHeader('WWW-Authenticate','DummyBasic realm="' . $this->realm . '"'); $response->setStatus(401); throw new \Sabre\DAV\Exception\NotAuthenticated('Cannot authenticate over ajax calls'); }

I have transfered the cloud installation to my local desktop (directory + database): In this environment the error does not occur. Therefore I cannot debug that.


  1. Very very (!) exact inspection of the settings in the nginx configuration and config/config.php: https://docs.nextcloud.com/server/latest/admin_manual/installation/nginx.html Be shure that is the description of the matching version!

  2. Deletion of the cookies