If you've ever come across Exception from HRESULT: 0xC00CEF03 when making configuration changes in IIS Manager (inetmgr.exe) or via appcmd.exe for IIS 8, 8.5, or 10, please check whether there is an <asm:assemblyBinding> section in your web.config.

IIS - Exception from HRESULT: 0xC00CEF03

The namespaced tag <asm:*> is the source of the problem, which ceases working since IIS 8, to fix this, you may

  • Remove the namespace:

    That is, change <asm:*> to <*>, and xmlns:asm to xmlns.

    For example, change this

    <?xml version="1.0" encoding="utf-8"?>
<configuration>
    <runtime>
        <asm:assemblyBinding xmlns:asm="urn:schemas-microsoft-com:asm.v1">
            <asm:dependentAssembly>
                <asm:assemblyIdentity name="Newtonsoft.Json" publicKeyToken="30ad4fe6b2a6aeed" culture="neutral" />
                <asm:bindingRedirect oldVersion="4.5.0.0-9.0.0.0" newVersion="9.0.0.0" />
            </asm:dependentAssembly>
        </asm:assemblyBinding>
    </runtime>
</configuration>

    to

    <?xml version="1.0" encoding="utf-8"?>
<configuration>
    <runtime>
        <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
            <dependentAssembly>
                <assemblyIdentity name="Newtonsoft.Json" publicKeyToken="30ad4fe6b2a6aeed" culture="neutral" />
                <bindingRedirect oldVersion="4.5.0.0-9.0.0.0" newVersion="9.0.0.0" />
            </dependentAssembly>
        </assemblyBinding>
    </runtime>
</configuration>

  • Or edit web.config manually.

References: