Jira REST "415 Unsupported Media Type" (Content-Type) in CI

By Daniel Zoghalchali·Latchkey

Jira returns 415 when it receives a body it will not parse as the declared type. For JSON endpoints, the request must send Content-Type: application/json; omitting it (curl defaults to form-encoding on -d) triggers a 415.

What this error means

A create, transition, or comment POST fails with HTTP 415 "Unsupported Media Type," even though the JSON body itself is valid.

HTTP/1.1 415 Unsupported Media Type
{"message":"Unsupported Media Type","status-code":415}

Common causes

Missing Content-Type header on a JSON POST

curl -d without an explicit header sends application/x-www-form-urlencoded, which Jira JSON endpoints reject with 415.

A wrong or duplicated Content-Type

A client library or proxy overrode the header to text/plain or set it twice, so Jira does not treat the body as JSON.

How to fix it

Set Content-Type: application/json explicitly

1. Add -H "Content-Type: application/json" to every JSON POST.
2. Add -H "Accept: application/json" so responses parse cleanly too.
3. Re-run the request to confirm the 415 clears.

curl -sf -u "$JIRA_EMAIL:$JIRA_API_TOKEN" -X POST \
  -H "Content-Type: application/json" -H "Accept: application/json" \
  -d '{"transition":{"id":"31"}}' \
  "https://your-domain.atlassian.net/rest/api/3/issue/ABC-123/transitions"

Confirm no proxy rewrites the header

If a corporate proxy strips or alters Content-Type, route Jira calls around it or configure it to preserve the header.

How to prevent it

• Always send Content-Type: application/json on Jira JSON POSTs.
• Set Accept: application/json so responses are JSON too.
• Prefer a client that sets JSON headers by default over raw curl -d.

Frequently asked questions

Related guides

References

• GitHub Actions documentation