Extension keeps de activating itself

[Rich Cleverley]

I have an extension (written by me) that for soem reason seems to keep deregistering itself within Magento. Basically it will be working fne then all of a sudden it's router starts returning a 404 and I can see other elements of the extension being reported as not existing (blocks being logged as not being registered etc).  If I clear the caches it starts working again but will eventually deregister itself again.

This isn;t something I've seen before and I'm really stumped with what might be causing it so if anyone else has had this occur it'd be great to hear about what you did to resolve the problem.

We are on Enterprise 14.1.1 with all patches applied running full page cache and APC.

[KuafuSoft]

maybe caching crashed, and you endup having an incomplete config xml in your cache, try update everything to the latest version (like apache/nginx, varnish, memcache and etc...) and see if it help

[Rich Cleverley]

 that's what I suspect.  I've put pur hosts on the case to see if they can see anything.

[KuafuSoft]

FYI https://github.com/convenient/magento-ce-ee-config-corruption-bug

[Rich Cleverley · Accepted solution]

Figured it out in the end.  The issue was Magento Enterprises Full Page Cache.  If the Ajax controller was being accessed directly in the browser or via a crawler it returned a 404 (this was explicitly set in the controller action as we don't want the controller doing it's work unless acess via a proper Ajax call). This was then caching in FPC whieh meant that any subsequent request also 404'd.

I have added an observer to the extension that forces the extension to not use FPC  and everything is fine.

So, it wasn't Magento losing configuration in teh end just FPC caching the 404.