Why are some entry detail views empty in the control panel? I can't seem to edit entry details all of a sudden: in this Products section (and only this one section), the page title and "Current Version" button will render, but the rest of the page is missing.



The only clue is this line from Craft's log:


  [31-Jul-2014 19:07:36 UTC] PHP Fatal error: Maximum function nesting level of '100' reached, aborting! in /Users/gob/projects/gobias/craft/app/vendor/twig/twig/lib/Twig/Node.php on line 140


I've loaded earlier MySQL backups, restarted MAMP Pro (PHP 5.5.10), cleared Craft's caches, tried different browsers and machines, and the problem persists.
That error isn't a Craft or PHP error, it's coming from older versions of xDebug.

It can happen on more complicated pages (lots of fields, tabs, etc.), but you can get around it by adjusting the xdebug.max_nesting_level to something higher than the default 100 or to upgrade xDebug to 2.3+, which has changed to the default value to 256.

Note that you don't have to have an active debug session going on in order to run into this, you just have to have the xDebug extension installed.