XF 1.5 Enable memcached, get random errors

We have memcached running on another server just fine and the two servers are able to communicate fine through the firewall. I can telnet from web server to memcached server no problem.

When I enable the memcached config in the XenForo config file, things appear to work OK, but after a few clicks, I start receiving errors. Sometimes it's completely generic (An error has occurred) and sometimes it's very specific. Here is one of the specific errors:

An exception occurred: Argument 2 passed to XenForo_Application::mapMerge() must be of the type array, boolean given, called in /home/devbb/public_html/library/XenForo/Dependencies/Public.php on line 304 and defined in /home/devbb/public_html/library/XenForo/Application.php on line 1174

XenForo_Application::handlePhpError() in XenForo/Application.php at line 1174
XenForo_Application::mapMerge() in XenForo/Dependencies/Public.php at line 304
XenForo_Dependencies_Public->preRenderView() in XenForo/FrontController.php at line 582
XenForo_FrontController->renderView() in XenForo/FrontController.php at line 158
XenForo_FrontController->run() in /home/devbb/public_html/index.php at line 13
Here is the XF config

$config['cache']['enabled'] = true;

$config['cache']['frontend'] = 'Core';

$config['cache']['frontendOptions']['cache_id_prefix'] = 'bb_';

//$config['cache']['cacheSessions'] = true;

$config['cache']['backend'] = 'Memcached';

$config['cache']['backendOptions'] = array(

        'compression' => false,

        'servers' => array(

                'host' => '',

                'port' => 11211


Memcached has 512M available to it.

Any ideas? As soon as I disable memcached in the XF config, things start working. Likewise, if I restart memcached, XF will start working again for a short time. This is currently just a dev site and I'm the only one hitting it, so I need to figure out what's going on.


XenForo developer
Staff member
How many styles do you have? Do you have styles or add-ons that are adding a lot of style properties?
This is a stock installation using the stock theme. Lots of nodes, lots of usergroups, and 8mil posts, though, if that would have any effect.

Also, it's not always a mapMerge error. Sometimes it's another method (Sorry, can't recall which) that pops up.


XenForo developer
Staff member
It sounds like Memcached is just giving inconsistent results then, which is very strange. It would appear to actually be giving back partial values or some corrupted value. Unfortunately, I'm not sure what would cause that (we use Memcached here without issue).
It's weird. We're using memcached on this server for other sites (no other XF) and it works fine. If memcached were running out of index (I mean configured space, not available space in RAM/disk) do you think it could cause weirdness like this?


XenForo developer
Staff member
Memcache should just be dropping older values, but I suppose it's possible.

I can check the raw values being returned if I can get FTP access while the issue is happening. If that's something you're interested in, please submit a ticket via your customer area.