I'm running into a really weird issue and I would appreciate any guidance on what I'm doing wrong. So I recently applied for an API key here on Stack Exchange and it went through fine. So let's say (for example) I received the following API key:


So using this key, I'm attempting to run a simple query like:


And I get the message:

    "error_id": 400,
    "error_name": "bad_parameter",
    "error_message": "`key` doesn't match a known application"

Am I using the API key correctly?

Note that I didn't want to post the real API key here for obvious reasons but if need be I can provide it.

  • I am encountering the same problem currently... And my authentification key is a 2.0 API key... api.stackexchange.com/2.2/…*pWtt4j88or54fjzQ%28%28%22&tag=%22C%22&fromdate=1230768000&todate=1230768000 </code>
    – Yulia M
    Apr 6, 2016 at 12:42

1 Answer 1


Tim Stone pointed out that I was trying to use a 1.1 key with the 2.0 API, which of course doesn't work.

I've registered for a 2.0 API key and everything is sorted out now.

  • 1
    note, this can also occur if you accidentally mix up your secret and key (or supply invalid key in general) Mar 10, 2015 at 2:29
  • 2
    I am encountering the same problem currently... And the answer provided here doesn't seem to help... My authentification key is a 2.0 API key... I have copied it from my application page (stackapps.com/apps/oauth/view). But the request still gives an error: api.stackexchange.com/2.2/…*9VFD9SysYMOxJEoKLj2Q%28%28%22&tag=%22C%22&fromdate=1230768000&todate=1230768000
    – Yulia M
    Apr 6, 2016 at 12:58
  • same here... after several years :(
    – gion_13
    Oct 10, 2019 at 22:39

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