JIRA Cloud REST API : Forbidden (403) error

The solution in the end was to use Basic Authentication via the Authorization header when issuing requests to JIRA's Cloud REST API: https://CLOUDID.atlassian.net/rest/api/3/APIMETHOD Headers: 'Authorization': 'Basic ZGFjcmVAb...', 'Accept': 'application/json' Basic authentication will be removed in the future according to the API documentation , so this is being treated as a stop-gap solution.

Context: Stack Overflow question (score 2, has accepted answer): I'm trying to utilise the JIRA Cloud REST API in an application I'm developing. Recently I've started getting 403 errors. My integration was reliable up until about a week ago, however these error responses have started to become very frequent. I've followed the documentation for 3LO code grants . Currently, I have: an application called "App" setup under the application dashboard in the application dashboard, my "App" has access to both "Jira platform REST API" and "Authorization code grants" under "Jira platform REST API" for my "App", the View Jira issue data and View user profiles options are both added/enabled When trying to authenticate with the JIRA Cloud REST API, everything seems to work as expected. I begin by redirecting the user to authorise "App" to access data from JIRA via h