How do I fix this problem and how do I login again?
The Piwik Super User can manually edit the file piwik/config/config.ini.php and add the following lines:
[General] trusted_hosts = "stuartmcmillen.net"After making the change, you will be able to login again.
You may also disable this security feature (not recommended). To do so edit config/config.ini.php and add: