Welcome to our community!
I’m sorry, I’m not very familiar with using our API, but I’ve forwarded your question to our developers for further advice.
In the meantime, I think you have seen the API documentation, but just in case, here’s the section on adding issues.
Perhaps it might be the URL, it’s from the documentation for adding issues:
Can you try using the URL as https://fedomenike.backlog.com/api/v2/issues?apiKey=MYKEY instead?
Because if you were making a test request to the below
you should get a positive 200 response. ( Not forgetting to swap in your own Backlog domain and apiKey in the above URL.)
So I suspect it’s the URL endpoint. Because it’s different URL endpoints for different requests: adding issues, get user, get project, etc.
For the JSON form parameters in the adding issues request, there are also some required parameters like projectId, summary, etc., listed in the documentation.
Perhaps you can try using an online API request builder too, for example, Hoppscotch (https://hoppscotch.io/) because it might be easier for API testing purposes.