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MickLang-8011 asked SamWu-MSFT commented

Exception configuring failed request tracing rule

Getting the following error clicking finish on the Add Failed Request Tracing Rule in IIS v10.0.17763.1...

There was an error while performing this operation.


Exception from HRESULT: 0xC00CEF03

Stripped down to just the offending section, the web.config looks like this...

 <?xml version="1.0" encoding="UTF-8"?>
         <binding name="fred">
           <security mode="TransportWithMessageCredential">
             <message establishSecurityContext="false">
                 <trust:SecondaryParameters xmlns:trust="">

Deleting lines 10 & 11 (the <trust:SecondaryParameters> tags) resolves the issue.

I can't see anything wrong with the XML causing the issue. Is this a bug?

I can confirm we're not experiencing this issue in earlier versions of IIS.

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1 Answer

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SamWu-MSFT answered SamWu-MSFT commented


0xC00CEF03 error code translates to WR_E_NSPREFIXWITHEMPTYNSURI which refers to "Writer: It is not allowed to declare a namespace prefix with empty URI"(Reference).

This error occurs when there is something wrong with the web.config file. It’s probably corrupted or there are incompatible tags and parameters. As a result of this corruption and incompatibility, IIS is not able to read this file. Therefore, it can’t make a change.

The issue mostly happens after migration because a piece of configuration that works in the older version of IIS (and .NET Framework) probably became unsupported in the newer version.

Solution for the 0xC00CEF03 error is find what part of the web.config is causing the issue is to remove sections one by one and test, this seems to be the method you are trying.

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You have the web.config above. If it's corrupted tell me where and how it's corrupted

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IIf this thing had a down arrow on the score for the comment I'd click it. My question basically inferred I already knew this error is associated with a corrupted web.config, yet you tell me ... 'ah your config is probably corrupt' without even bothering to try the config supplied in the question which I said reproducing the issue. I'd suggest don't even bother answering questions if this is the quality of your response.

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@MickLang-8011 I analyze the problem based on the error message you posted. I don’t have the relevant configuration information in your iis to reproduce your problem. I answered above that this is likely to be caused by incompatible versions, if you need more help, I suggest you open a case via : In addition, this is an exchange community. Anyone who expresses their own opinions should not ask others for answers as a matter of course. you need to do it yourself more.

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I've replicated it on multiple machines, the configuration listed above does reproduce the issue on the specified version of IIS running on Windows Server 2019

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