503 service unavailable due to “The Module DLL …compdyn.dll failed to load”

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Quickly helping one of colleague where after restoring applicationhost.config from the back up on win2k8 IIS 7 we started receiving 503 Service Unavailable on the browser.

As the very first step was to check event viewer where we had the following logged:

Log Name: Application
Source: Microsoft-Windows-IIS-W3SVC-WP
Date: 7/28/2009 12:46:10 AM
Event ID: 2280
Task Category: None
Level: Error
Keywords: Classic
User: N/A
Computer: <computer_name>
Description:
The Module DLL C:\Windows\System32\inetsrv\compdyn.dll failed to load. The data is the error.

compdyn.dll ==> Dynamic Compression

Checking the inetsrv folder we were not able to locate this dll.That’s interesting.

Option provided was to :

1) Either to turn off the dynamic compression in applicationhost.config

  • appcmd.exe set config "Default Web Site" -section:system.webServer/urlCompression /doDynamicCompression:"False"

2) Or to install the dynamic compression modules from Add Role Services Wizard, select Dynamic Content Compression

Enlarge

Till then bye bye …