Problem mapping HttpHandler --> HTTP Error 404 Not Found

Just as a guide for those stuck with this problem I found the crucial attribute to be..

resourceType="Unspecified"

I originally followed a Microsoft example to set this up and they had it as

resourceType="File"

which just kept giving me 404 errors. My HTTPHandler is returning graphics.

Hope this helps :)

What is the extension of your handler? If you are using a custom extension like .hndlr you may also need to add a ScriptMap in IIS and point it to the ASP.NET runtime so that IIS can forward the request to the correct processor.

---

1. In IIS7 go to your website
2. Under the IIS group go to Handler Mappings
3. Under Actions click Add Script Map
4. Set Request Path to *.hndlr
5. Set Path to the ASP.NET runtime (%windir%\Microsoft.NET\Framework64\v2.0.50727\aspnet_isapi.dll) or whatever version you are running.

Then in your web.config you will need to register the handler in the appropriate section as described in the other answer.

i am using IIS7, the solution is:

in section

<system.web>
    <httpHandlers>
        <add verb="*" path="*.ashx" type="CVOS.MyDocumentHandler"/>
    </httpHandlers>
<system.web>

and section

<system.webServer>
    <handlers>
       <add name="pdfHandler" verb="*" path="*.ashx"   type="CVOS.MyDocumentHandler" /> 
    </handlers>
</system.webServer>

Are you using IIS7, if so is the application pool running in classic or pipelined mode? If it is IIS7 in pipelined mode then the handler reference needs to go into the following section

<system.webServer>
    <handlers>
    </handlers>
<system.webServer>

rather than in the following section.

<system.web>
    <httpHandlers>
    </httpHandlers>
</system.web>