I get RefererNotAllowedMapError in console, and the whole screen is gray. But, at the bottom of the Mashup specification, there is changelog where it says that we don't need to get an API key.

Should I obtain an API key?

  • Are you taking CS50x on edX? If so, some of the psets have changed for 2019. mashup has been retired. Detail can be found on the course home page. The default index.html in the 2018 distro code has an API key, and you can access google maps "for development purposes only". The map is visible underneath; all the project API's work. It usually gives console errors This API project is not authorized to use this API...... and You have exceeded your request quota for this API...... Commented Jan 31, 2019 at 22:01
  • Yes, CS50 on edX. I didn't finish course in time, so I just continued from where I stopped (pset8, mashup). So mashup isn't in the curriculum any more? I am working on it whole day lol :D Commented Jan 31, 2019 at 22:20

1 Answer 1


As mentioned in the comment, Mashup has been retired for the 2019 course. You of course can still work on it if you'd like, but if you are going for a certificate, it cannot be submitted for a grade.

If you do, you will need to get your own API key (note that Google now requires a credit card in order to receive a key).

If you are going for a certificate, be sure to visit the course's homepage and follow the instructions in the yellow box that explain how to transition from the 2018 to the 2019 course.

  • Thanks for answering! One more question: when I go to pset5 page on edX, there is only Homepage task. I am confused because on the page you linked there are instructions for skipping psets (depending of what you have finished) which doesn't exist as far as I can see. Commented Feb 1, 2019 at 11:28
  • The link simply says you can skip psets6,7,8. There aren't further instructions about skipping. You need to complete pset5 for full credit (if you are trying for the certificate)
    – curiouskiwi
    Commented Feb 1, 2019 at 18:22

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