One day I updated my Matomo installation with web based updater. I was suprised that after that I couldn’t login.
I got following error message:
Form security failed. Please reload the form and check that your cookies are enabled. If you use a proxy server, you must configure Piwik to accept the proxy header that forwards the Host header. Also, check that your Referer header is sent correctly.After searching thru the forums I didn’t get any helpful clue. So I decided to read entire error message carefully 🙂 And it says what it wants: “Also, check that your Referer header is sent correctly.”
The solution is to add/change you referrer header like this in your virtual host config file or .htaccess file:
Header set Referrer-Policy “same-origin”