Update from 310.0.5 to 31.0.6 breaks notify-push

I haven’t encountered this issue on my instance. Are you sure it actually worked before the update, and that the issue wasn’t already there and just went unnoticed?

The error message provides some hints what to check:

There was an error setting the notify_push server URL. Please double check your reverse proxy settings as well as the overwrite.cli.url entry in Nextcloud's config.php

So please double check if the notify_push service is running, and if everything is configured correctly according to the documentation, especialy the reverse proxy config of your webserver.

Also make sure thet the trusted_domain, overwrite.cli.url and trusted_proxies settings are set correctly in your config.php. If everything is running on the same machine they should look something like this:

'trusted_domains' => 
  array (
    1 => 'cloud.yourdomain.tld',
  ),

  'overwrite.cli.url' => 'https://cloud.yourdomain.tld',

 'trusted_proxies' => 
  array (
    0 => '127.0.0.1',
    1 => '::1',
  ),

…then run:

occ notify_push:setup "https://cloud.yourdomain.tld/push"

If it still doesn’t work, please post the output of the above command here and fill out the support template. Otherwise, we’re flying blind here.