HTTP Error 500 in IIS

[Techguy817]

I am running the MindTouch Core 10.1.3 CMS web application on a 2008 R2 SP1 server and am running into issues. I have posted the issue over on those forums and ServerFault but I think it is more related to PHP itself and the environment. The problem doesn't happen locally with a similar VM on our network, just on the public one hosted online.

 

Basically, every few hours or so, we will receive an HTTP error 500 message either in the browser or in the logs. This happens when browsing pages and is especially reproducible when uploading files (usually between 5-10MB). Simply refreshing the page or trying to upload the file again will allow it to eventually complete.

 

In IIS, I see several entries of the following under FailedReqLogfiles:

 

ModuleName ManagedPipelineHandler

Notification 128

HttpStatus 500

HttpReason Internal Server Error

HttpSubStatus 0

ErrorCode 0

ConfigExceptionInfo

Notification EXECUTE_REQUEST_HANDLER

ErrorCode The operation completed successfully. (0x0)

 

 

The PHP version is 5.2.14 (version that ships with MindTouch). I will also see some entries in the PHP error log that show:

 

[05-Mar-2013 15:03:31] PHP Warning: implode() [<a href='function.implode'>function.implode</a>]: Invalid arguments passed in C:\Program Files (x86)\MindTouch\MindTouch\web\skins\error-settings.php on line 93

 

The server is a virtual machine with 4GB RAM and 4 vCPUs. It is hosted in the cloud and accessible over the web.

 

What things can I look at to troubleshoot this issue? Are there settings on the properties of the App Pool that I should review? Any help is greatly appreciated.