Update Error 3.9.1

I have this issue since Updating to 3.9.1 or is it because of an Apple Security Update?

I have updated on two domains. One update process on one domain caused several
errors but they somehow disappeared now. But the login is really annoying.

Jeeeeesus christ … IT developers … the never ending failure story.


Error : Form security failed. Please reload the form and check that your cookies are enabled. If you use a proxy server, you must configure Matomo to accept the proxy header that forwards the Host header. Also, check that your Referrer header is sent correctly.


Do you use a reverse proxy in front of your Matomo instance?