TeamCity 9 uses WebSockets for UI updates. If you are using TeamCity 9 behind an Apache proxy, you will have to make some changes to the configuration for TeamCity 8.
Make sure you are using version 2.4.5 or newer:
$ apachectl -V
Enable the Proxy WebSockets tunnel module:
$ sudo a2enmod proxy_wstunnel
Add the following ProxyPass rules to the Apache site configuration of your TeamCity installation - usually located in
ProxyPass /app/subscriptions ws://localhost:8543/app/subscriptions connectiontimeout=240 timeout=1200 ProxyPassReverse /app/subscriptions ws://localhost:8543/app/subscriptions
Important: Add those lines directly above the already existing ProxyPass rule.
The port has to be the same you used in the TomCat configuration of your TeamCity installation (see figure 8).
$ sudo service apache2 restart