Root cause of an error is not displayed when saving a page on Tomcat

Preconditions: XWiki Realtime Edit feature has to be disabled to better observe the issue.

Steps to reproduce

1. Create a page
2. Edit the page and insert a very long title (> 800 characters)
3. Save the page using Save & View
4. Save the page using Save & Continue (or Save)

Expected results

The notification on the bottom of the browser page contains the exception reason.

Actual results

The error is general:

Failed to save the page. Reason: Server not responding

The issue doesn't reproduce on Jetty.