Recently while working I faced an issue where the website (IIS 7) was showing 503-Internal Server Error. Checking Event viewer shown following Events for IIS

The Module DLL C:/Program Files/IIS/Advanced Logging/ClientLoggingHandler.dll failed to load. The data is the error. The Module DLL C:/Program Files/IIS/Advanced Logging/AdvancedLoggingModule.dll failed to load. The data is the error.

Complete Event in Event Viewer was

Log Name: Application
Source: Microsoft-Windows-IIS-W3SVC-WP
Date: 12/8/2009 11:33:23 AM
Event ID: 2280
Task Category: None
Level: Error
Keywords: Classic
User: N/A
Computer: WIN-AD50B4LJ2SU
Description:
The Module DLL C:/Program Files/IIS/Advanced Logging/AdvancedLoggingModule.dll failed to load. The data is the error.

Both the DLL’s which were mentioned in the Event we present in respective Directories but still IIS was not able to detect them. So, to fix the issue

1) Copy “C:/Program_Files/IIS\Advanced_Logging/ClientLoggingHandler.dll” and “C:/Program_Files/IIS/Advanced_Logging/AdvancedLoggingModule.dll” to %windir%/System32/

2) Edit C:/Windows/System32/netsrv/config/applicationHost.config and Search for following Lines

add name=”ClientLoggingHandler” image=”%ProgramFiles%/IIS/Advanced Logging/ClientLoggingHandler.dll” add name=”AdvancedLoggingModule” image=”%ProgramFiles%/IIS/Advanced Logging/AdvancedLoggingModule.dll”

and change it to

add name=”ClientLoggingHandler” image=”%windir%/System32/ClientLoggingHandler.dll” add name=”AdvancedLoggingModule” image=”%windir%/System32/AdvancedLoggingModule.dll”

3) Restart IIS