IIS failed request trace logs are inconsistent across all applications.

Gern Blandsten 0 Reputation points

We are having a problem with IIS Failed Request Tracing, not all websites are generating the XML logs.  We have a Windows Server 2016, IIS 10.0 with one default web site and three application pools and applications.  The Failed Request Tracing has been set up at the default web site and for each application.  The exact problem is one of the sites does not generate a file in the FailedReqLogFiles folder, while the other two do.  Without the XML Log we are unable to troubleshoot errors. 

Thanks for any ideas!

We have done/checked the following: 

  • FREB is enabled 
  • Checked that the log path is correct 
  • The application pool identity has permissions to write to log path 
  • Maximum Requesting Entity Body Limit increased to 3000000 

The web.config looks like this:


                <remove path="*" /> 

                <add path="*"> 


                        <add provider="ASP" verbosity="Verbose" /> 

                        <add provider="ISAPI Extension" verbosity="Verbose" /> 

                        <add provider="WWW Server" areas="Authentication,Security,Filter,StaticFile,CGI,Compression,Cache,RequestNotifications,Module,FastCGI,WebSocket" verbosity="Verbose" /> 


                    <failureDefinitions timeTaken="00:00:00" statusCodes="401-505" /> 



Internet Information Services
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  1. Sam Wu-MSFT 7,036 Reputation points Microsoft Vendor

    @Gern Blandsten

    What requests or settings have you made for the site that does not generate a failed request tracking file? The reason why the log file is not generated may be that the request does not enter IIS. You can use Fiddler to capture your request and view the detailed request process.

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