Push notification sent but response was not parsable, using an outdated push proxy

[xinstein]

Steps to reproduce

1. ./occ notification:test-push --talk {username}

Expected behaviour

notifications should send and no error should raise

Actual behaviour

notification is sent but a funny info message is recorded:

Push notification sent but response was not parsable, using an outdated push proxy? [https://nc.xstereo.top:7443/index.php/apps/ssepush] : {Followed by sth looking like the html of my nextcloud homepage.}

Server configuration

Operating system:

Web server:

Database:

PHP version:

Nextcloud version: (see Nextcloud admin page)

Where did you install Nextcloud from:

Signing status:

Login as admin user into your Nextcloud and access
http://example.com/index.php/settings/integrity/failed 
paste the results here.

List of activated apps:

If you have access to your command line run e.g.:
sudo -u www-data php occ app:list
from within your ownCloud installation folder

Nextcloud configuration:

If you have access to your command line run e.g.:
sudo -u www-data php occ config:list system
from within your ownCloud installation folder

or 

Insert your config.php content here
Make sure to remove all sensitive content such as passwords. (e.g. database password, passwordsalt, secret, smtp password, …)

Are you using an external user-backend, if yes which one: LDAP/ActiveDirectory/Webdav/...

Client configuration

Browser:

Operating system:

Logs

Nextcloud log (data/owncloud.log)

Insert your Nextcloud log here

Browser log

Insert your browser log here, this could for example include:

a) The javascript console log
b) The network log 
c) ...

[xinstein]

https://github.com/nextcloud/notifications/issues/773 looks like this one but never goes away

[joshtrichards]

using an outdated push proxy? [https://nc.xstereo.top:7443/index.php/apps/ssepush]

What is ssepush?

[xinstein]

it's a third-party push implementation which enables push on googless phones.

https://gitlab.com/Nextcloud-Push/nextcloud-push-notifier

I've been using it for years now, pretty stable and battery-efficient

using an outdated push proxy? [https://nc.xstereo.top:7443/index.php/apps/ssepush]

What is ssepush?