The jira server is EE 9.17.5
I use this endpoint URL (/rest/api/2/issue/<jira-ticket-key>?fields=key,summary) to retrieve the jira ticket info, with Authorization header, and Accept header set to application/json.
It seems the rest server needs warm up. The first couple tries always come back with 500 code (internal server error); eventually the GET request comes back with 200 code, with content in JSON format.
Then I tried with the v3 api (/rest/api/3/issue/<jira-ticket-key>?fields=key,summary) with exactly the same headers. The response code is 200, but the content is in HTML format.
