I'm simply attempting to set up a Custom Domain in API Gateway. I have ACM certificate "*.mysite.com.au" that is currently being used to serve a static S3 website out via CloudFront at "beta.mysite.com.au". I wish to create a custom domain for "api.mysite.com.au" with this certificate.

However, I'm receiving the following error in the AWS API Gateway console:

The domain name you provided is already associated with an existing CloudFront distribution. Remove the domain name from the existing CloudFront distribution or use a different domain name. If you own this domain name and are not using it on an existing CloudFront distribution, please contact support.

I'm not currently using "api.mysite.com.au" in a CloudFront distribution. So I'm lost. Has anyone encountered this issue before? And if so, how may I go about resolving it?

Thanks in advance,


  • 1
    What did AWS support say when you asked them? – Matt Houser May 22 '17 at 1:12
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    Only paying for a basic plan at the moment, so I thought I'd push it out to Stack Exchange just in case I'm missing something. – Strainy May 22 '17 at 1:13
  • Check DNS for a record that relates your domain to cloudfront. – Landon Kuhn May 3 '18 at 16:47

There are three, maybe four possibilities:

  • you have in fact configured this domain as an Alternate Domain Name in CloudFront -- in this AWS account or in another account and you've forgotten about it, or

  • someone else has accidentally or deliberately configured this domain on a CloudFront distribution, or

  • you already configured this in API Gateway, but in a different AWS Region, or

  • this is a bug in the integration between API Gateway and CloudFront.

To troubleshoot:

Go to CloudFront and create a new distribution.

Try to set this hostname as an alternate domain name.

If that works, then this seems like a bug in the API Gateway/CloudFront integration. Delete the hostname from Alternate Domain Names for that new distribution, wait a few minutes for the distribution to go back to Deployed status, then try again in API Gateway. (Later, delete the distribution -- it isn't needed).

But, I'm going to assume that the above will not work. You should get an error from CloudFront, CNAMEAlreadyExists. (It's not really a CNAME but that's what they unfortunately called it.)

So, follow the official process to prove ownership and control of your domain name and associate it with the new CloudFront distribution.

This process should release that hostname from whatever CloudFront distribution is claiming it.

Once that completes, remove this hostname from the Alternate Domain Names setting of the new distribution, save changes, wait for it to return to the Deployed state, and go back to API Gateway and try again. (Later, delete the unused distribution.)

The issue here is that -- just like the S3 bucket namespace -- the CloudFront front-end Host: header namespace is global. A hostname can't be associated with more than one CloudFront distribution, including the "stealth" distributions that API Gateway uses. The error implies that the one you're trying to use, for some reason, already is.

This should be unrelated to a wildcard you may have from ACM.

  • Note that you might try opening this under Account & Billing Support > Account > Other Account Issues. There seems to be a limited set of techical issues that they can address for you at no charge via that route, like disabling EC2 Classic on your account so that you can have Default VPCs, the way I had to do here on SF... although they might also direct you to the doc above. – Michael - sqlbot May 22 '17 at 2:38

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