Appstore API proxy error

Nextcloud version (eg, 12.0.2): 13.0.5
Operating system and version (eg, Ubuntu 17.04): Ubuntu 16.04
Apache or nginx version (eg, Apache 2.4.25): Apache 2.4.18
PHP version (eg, 7.1): PHP 7.2.9

The issue you are facing:
When upgrading Nextcloud (via admin manual upgrade) my apps dont get updated and are all being disabled after performing the upgrade command. So I searched in the log file and found an exception caused by returning 502: Proxy error. Is this intentional (maybe because of deprecation)?

Is this the first time you’ve seen this error? (Y/N): Y

Steps to replicate it:

  1. Upgrade Nextcloud according to
  2. Run sudo -u www-data php occ upgrade
  3. All apps are disabled

The API is accessible again, maybe this does the trick… Maybe this thread can be closed already.