Error 500 on IIS 8/8.5 with ColdFusion 10/11

Question

If I have an error in my ColdFusion script, I'm getting a 500 error message from IIS instead of ColdFusion. This only happens if I provide the file name in the URL and does not happen if I open the URL without the script name (which would open index.cfm).

For example:

• IIS error: http://www.example.com/index.cfm
• IIS error: http://www.example.com/foobar.cfm
• Coldfusion error: http://www.example.com/

I can reproduce this problem on 2 of my 3 ColdFusion platforms:

• Working: IIS 7.5 with ColdFusion 10 Update 12 (with updated connector)
• Not Working: IIS 8 with ColdFusion 10 Update 12 (with updated connector)
• Not Working: IIS 8.5 with ColdFusion 11

My index.cfm & foobar.cfm:

<!--- provoke a coldfusion error --->
<cfset foo

My web.config:

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <system.webServer>
        <httpErrors errorMode="Custom" existingResponse="PassThrough" />
    </system.webServer>
</configuration>

For me it looks like there's a problem with the ColdFusion connector with IIS 8 and IIS 8.5.

Answer 1

Okay, I was finally able to fix this.

The problem

I run multiple web applications each in a own virtual directory under the same IIS website. It turned out that adding existingResponse="PassThrough" to the web.config only works partially in virtual directories. Without that setting I never get any ColdFusion error and instead I always see the IIS 500 error. If I add existingResponse="PassThrough" in the web.config of a virtual directory, ColdFusion errors are only forwarded if you access the site without calling a .cfm script directly (for example: example.com/ instead of example.com/index.cfm).

The solution

The solution was easy. I just had to add the existingResponse="PassThrough" setting to the web.config of the root IIS website aswell and everything is working.

I think this is a bug in IIS 8 and 8.5 since I double checked that on my IIS 7.5 server and I didn't had to add the property on the root website.