How to investigate Disconnect failures

This article will guide you on how to investigate disconnect failures. An example of such a failure

Disconnect failures happens when one side is closing the connection and Mozmill is unable to send the information over the bridge or when Firefox crashes. Usually disconnects happens when a modal dialog freezes and we cannot close it sp we close Firefox with the modal frozen. We cannot investigate failures via mozmill, because we do not catch the crashes, so the crashes' information is not logged; we have to go to ci machines and investigate directly.

  1. Check if Firefox crashed:


[user]/AppData\Roaming\Mozilla\Firefox\Crash Reports

[user/home]/.mozilla/firefox/Crash Reports
And there we can check by timestamp if Firefox crashed when we had the disconnect.

  1. Check the Event Viewer to check if an OS event interfered with the test run.

The event viewer can be found on Windows:

Computer Management > Event Viewer > Windows Logs > Application

And here we look for errors that overlapped with the test run; we cannot see the freezes (the main thread is blocked).

Crashes (not freezes)

  1. If we have a crash we always should submit it.
  2. Under about:crashes we have links to all the crashes submitted by Firefox to crash-stats.
From there use “Signature” as summary for bugzilla bug.
In “Extensions” check installed addons and check if they might be responsible for the failure.
3. Single out the failing test or shorten the required tests needed to reproduce.
4. Reproduce manually if possible.

File a bug

Once you found what caused the failure, file a new bug; if you could make it reproducible, narrow down the test case as much as you can so we can see what causes the failure.