Connect Spring Boot: POST Attachment returns 401 when acting as Add-on, but works when acting as User

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Hi everyone,

I am developing a Jira Cloud app using Atlassian Connect Spring Boot. I am running an task to upload an attachment to an issue using POST /rest/api/3/issue/{issueIdOrKey}/attachments. upload attachment

The Issue: Previously, I was able to upload attachments using the standard add-on authentication it worked.
However, I am now receiving a 401 Unauthorized error when using authenticatedAs() suddenly from 21-JAN-2026.

Observations:

  1. When I explicitly impersonate a user using authenticatedAs(AtlassianHostUser), the upload works perfectly.

  2. When I use authenticatedAs(), the upload fails with 401.

  3. My app descriptor has the WRITE scope.

Code Snippet (Failing):


RestTemplate restTemplate = atlassianHostRestClients.authenticatedAs();
// ... POST request to /attachments ...
// Result: 401 Unauthorized

Code Snippet (Working):

AtlassianHost host = atlassianHostRepository.findByClientKey(clientKey).get();
AtlassianHostUser hostUser = AtlassianHostUser.builder(host).withUserAccountId(userAccountId).build();
RestTemplate restTemplate = atlassianHostRestClients.authenticatedAs(hostUser);
// ... POST request to /attachments ...
// Result: 200 OK

Question: Does the “Create Attachment” endpoint related changes by atlassian as i not able to seed any changes in changlog of REST API.

Any insights would be appreciated!