Other posts on the topic

The API is no longer sending Cross-Origin Resource Sharing (CORS) headers after 180 calls

You can replicate it from any browser using the code below.

Every time I run it, it fetches 180 pages at an average rate of 5.51 calls per second.

On the 181st call I get: Cross-Origin Request Blocked

This affects all API calls to all sites and is wreaking havoc with multiple userscripts that rely on the API, but get a CORS error and will not process the response.


1 Answer 1


Thanks for reporting! A fix for this was just deployed, and the CORS headers are getting sent again.

  • 2
    Wow! That was fast from when this was reported here on MSE! Thanks for getting it done!
    – Makyen
    Commented Nov 14, 2019 at 23:46
  • 3
    I've written up a more detailed answer on SO: meta.stackoverflow.com/a/391352/155005
    – m0sa
    Commented Nov 14, 2019 at 23:56
  • Just FYI: using the code in this Stack Apps answer to test indicates that the change made to resolve the larger, more important issue did not resolve the problem reported in the Stack Apps bug report from a few months ago. Note: please see my last comment on the answer I linked for a complication to testing (i.e. I did not encounter the problem the second time I tested, but with a key value in the requests).
    – Makyen
    Commented Nov 16, 2019 at 19:38

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .