Summary

Tomcat supports a setting of -1 to create an unlimited session timeout. When setting an unlimited session-timeout for Tomcat in <confluence-install>/conf/web.xml or <confluence-install>/confluence/WEB-INF/web.xml, instead of setting an unlimited session it prevents sessions from working as expected.

Steps to Reproduce

1. Install Confluence 5.8 or above (from tar.gz with system Java 8 JDK installed)
2. Edit <confluence-install>/confluence/WEB-INF/web.xml:
   1. <session-timeout>-1<session-timeout>
3. Start Confluence
4. Create a new page
5. Save

Expected Results

The page saves as expected

Actual Results

The below exception is shown in the browser:

Your session has expired. You may need to re-submit the form or reload the page.

Workaround

Set a session timeout higher than 0 (for example, if your intent is to not have sessions timeout during the workday set it to 540)