Firefox v57 notice:
'Extension Conflict Troubleshooter for Firefox' is considered a 'legacy' extension and will no longer work with Firefox v57 and above. 'Extension Conflict Troubleshooter for Firefox' cannot be written with the WebExtensions platform that Mozilla has adopted for all extensions. 'Extension Conflict Troubleshooter for Firefox' will still be maintained, but only for Firefox clones (like Pale Moon).
With the literally thousands of add-ons available for Firefox, some are bound to conflict with each other. This extension is designed to help find conflicting extensions.
If you install a new extension and you immediately notice that one of your previously installed extensions stops working, it's a good guess that the new extension caused the problem. But what if the problem is not noticed right away or is a subtle change (like a menu item goes missing or some less-used function of the extension is no longer working)?
One method of finding the conflicting add-on is to disable each of your extensions one by one until you find the culprit. If you have more than just a handful of extensions, this can be very time consuming. A more efficient method would be to disable only half of the extensions then test to see if the conflict is resolved. If it is, then you know the culprit is one of the disabled extensions. If not, you need to re-enable those extensions and disable the other half. You go back and forth disabling/enabling extensions until you whittle down the list to a single culprit. While the most efficient method, it can be very confusing keeping track of which extensions to disable/enable.
This is what FECT does. A FECT session consists of several iterations of different extension configurations. It will randomly disable/enable one half of the installed extensions during each iteration depending on how you answer the question "Was the conflict resolved?". During my test runs, FECT was able to determine the culprit extension after about five to seven iterations (with 42 installed extensions).
This is the first alpha release. I would appreciate any help testing/debugging. You don't have to have a true conflict to test, just assume beforehand that one particular extension conflicts with the "target" extension and proceed through the iterations. In the FECT dropdown menu there is an item to "Display progress report" that summarizes the progress of the session.
To start a session, select "Start a new session" from the FECT menu and choose a target extension (this is the one that no longer works correctly). After FECT restarts Firefox, you can select "Continue with next iteration". Each time, Firefox will be restarted with the new configuration. When you are done, select "End current session" and FECT will reset Firefox to the way it was before the session was started.
After first installing FECT, you should place the FECT icon on on of your toolbars for easy access (right-click on the toolbar, select 'Customize...' then drag/drop the icon to somewhere appropriate).