I have a site hosted on Google AppEngine (e.g. myapp.appspot.com).
I have another site hosted on Hetzner using my own domain name. (e.g. mysite.info).
I have set up a CNAME record on Hetzner, which resolves the subdomain testsubdomain to myapp.appspot.com.

I have used this site to check that the CNAME record has been propogated to DNS servers, and it shows that testsubdomain.mysite.info is indeed resolved as myapp.appspot.com

If I type myapp.appspot.com into a browser the AppEngine site loads.
But if I type testsubdomain.mysite.info into a browser I get a 404.

I have cleared my browser cache (Firefox) and tried another browser (Chrome).
I have also tested through another ISP from my mobile phone (3G/Opera Mini instead of ADSL)

Any suggestions as to what might be the problem or how I can resolve this?

  • 2
    Have you configured appspot? Just pointing a domain at appspot is not enough. They need to know that the domain is associated with your account and your content so that they can serve something other than a 404. Jul 14, 2016 at 9:51
  • @StephenOstermiller The appspot is configured in the sense that I have my own website set up on my Google AppEngine account running at a url similar to myapp.appspot.com Browsing directly to myapp.appspot.com DOES serve my website, but browsing to testsubdomain.mysite.info gives the 404. Is that what you meant?
    – Andrew
    Jul 15, 2016 at 11:08
  • In general, you have to add every domain and subdomain you use to your hosting account. I've never used appspot, so I'm not sure how it works there, but they can't serve your subdomain unless you tell them about it. Jul 15, 2016 at 11:10

1 Answer 1


Before you can set up a CNAME entry for AppEngine you have to configure ApPEngine to recognise that CNAME entry.

In order to add a custom domain to your AppEngine application you need to log into the AppEngine console. Then you need to go to "Add a Custom Domain" and follow the steps to add a domain and verify domain ownership.

Once you have verified ownership of a domain you can add the appropriate sub domain into AppEngine. Once that has been done it will tell you the AppEngine endpoint to point your CNAME record to. Allow some time for DNS propagation and then test and it should then work.

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