A process serving application pool 'Classic .NET AppPool' suffered a fatal communication error with the Windows Process Activation Service. HTTP Error 503.

Question

Hi,

I am running an ASP.NET 3.5 web application on IIS 7 on Windows Server 2008.

I received the following error earlier this afternoon:

HTTP Error 503. The service is unavailable.

I looked in the Event logs and discovered that:

A process serving application pool 'Classic .NET AppPool' suffered a fatal communication error with the Windows Process Activation Service. The process id was '3328'. The data field contains the error number.

Here is the full details of that event:

Log Name: System Source: Microsoft-Windows-WAS Date: 18/09/2009 14:58:31 Event ID: 5011 Task Category: None Level: Warning Keywords: Classic User: N/A Computer: computername Description: A process serving application pool 'Classic .NET AppPool' suffered a fatal communication error with the Windows Process Activation Service. The process id was '3328'. The data field contains the error number. Event Xml: 5011 0 3 0 0 0x80000000000000 23552 System computername Classic .NET AppPool 3328 6D000780

This resulted in:

Application pool 'Classic .NET AppPool' is being automatically disabled due to a series of failures in the process(es) serving that application pool.

Here is the full details of that event:

Log Name: System Source: Microsoft-Windows-WAS Date: 18/09/2009 15:03:05 Event ID: 5002 Task Category: None Level: Error Keywords: Classic User: N/A Computer: computername Description: Application pool 'Classic .NET AppPool' is being automatically disabled due to a series of failures in the process(es) serving that application pool. Event Xml: 5002 0 2 0 0 0x80000000000000 23557 System computername Classic .NET AppPool

Concluding in the: HTTP Error 503. The service is unavailable.

Would someone please help me to identify how this happened and what I need to do to prevent it from happening in the future.

Thanks.

Kind Regards

Walter

Answer 1

This one is a pretty nasty one. I recommend getting the IIS Debug Diagnostics tools. You can probably alleviate the symptom by turning off "Rapid Fail Protection" in the properties of your application pool, but that will just mask the problem. What is going on is that your application is experiencing an exception so often/so repeatedly that the service shuts itself off. You'll need to run the diagnostic tool to capture everything going in and out to find the exception that's occuring.

This can be a very laborious task because the tool will gather gigabytes of junk to sift through. If you're lucky, the turning off of the "Rapid Fail Protection" might allow the exception to proceed through to the browser, but my guess is that the server will just end up hanging.

Answer 2

Its most likely caused by an infinite loop.

(I just had the same problem.) So you will just have to look for places in the code that use loops and see if removing one of them stops the error. Once you have found the culprit, then you can try to figure out whats causing it to loop indefinitely.

Answer 3

I had it, and in my case it seems related to another process consuming all the memory on the server.

Answer 4

uninstall IIS completely:

run cmd as administrator: start /w pkgmgr.exe /uu:IIS-WebServerRole;WAS-WindowsActivationService

then install IIS from add/remove programs -> features