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Fixing CF: "Hey, how come ColdFusion debugging output is not showing up in my localhost testing?"

This is a problem that has troubled many CF users for some years (especially as they have moved to later operating systems): they find that ColdFusion debugging output does NOT appear to them when testing using a URL with "localhost" for the domain name but it DOES appear if they use the ip address instead.

And sure, they could change to just using the ip address, but they wonder why it fails with "localhost" and whether they can fix things so that it does? In this post, I offer the explanation and solution.

In brief, the problem happens when the OS you're working on processes your "localhost" request via ipv6 (if it makes the request as ::1), rather than ipv4 (as
  • One option could be to edit your hosts file to force, and that should work
  • But another would be that if you knew about your localhost calling with the ipv6 address of ::1, you should be able to add that to your CF Admin "debugging ip addresses list" (or use its "add current") button. But you will find that if you try that, it will change to "0:0:0:0:0:0:0:1", which does not solve this problem. I have a workaround for that, editing the neo-debug.xml.
Adobe could fix that last problem (and I have filed a bug report, CF-4203295), but until they do, here's a workaround and explanation of things.

And this latter point, of the inability of the Admin to accept ::1--and on the matter of editing that file--is the real focus of this post.

[....Continue Reading....]

# Posted By Animesh Dutta | 8/24/18 10:25 PM
The easiest solution is just to open your hosts file and put localhost

This acts as a local DNS proxy and redirects all requests for "localhost" to

This actually solves quite a few other issues with using localhost that have plagued folks for years, not just CF related.
# Posted By Russ | 8/25/18 3:05 AM
Thanks, Russ. I had indeed mentioned the option of editing the hosts file and showed the value to use. But I saw on review that I had made a mistake in the value I showed, so I have corrected that. You didn't indicate seeing that but I do thank you for mentioning this and causing me to correct that.

I also tweaked the opening to make it more clear that that's an option (in the "in brief" section--which I added with you in mind, as I know you tend not to like "all the waffle".)

Again, though, "the waffle" is more for the matter of our need (for now) to edit the neo-debug.xml because CF doesn't accept adding the ::1 address for us. That's the real problem I wanted to point out, and how editing that file is a workaround, and the challenges with that.

And as I also noted later in the post, editing the hosts file does not always suit everyone. In the forum thread where this came up (mentioned in my bug report), a poster expressed that editing the hosts file had not worked for him. Again, I alluded to some of the possible challenges with that and decided not to make this a post about that but about the CF issue instead.

Still, again I have tweaked the post a bit based on your comment and I thank you for that.
# Posted By Charlie Arehart | 8/25/18 7:34 AM
Thank you so much. It worked!
# Posted By Kavita | 10/28/19 12:25 PM
Thanks for the feedback, glad to have helped.
# Posted By charlie arehart | 10/28/19 12:30 PM
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