All execution attachments return HTTP 400 – preview/download impossible

Site: kpn.atlassian.net
App: Zephyr Essential – Test Management for Jira, installed version 9.2.0 (Atlassian shows “Outdated”)

Problem
No test execution or test step attachment can be previewed or downloaded. Thumbnails show as broken images, and the download spinner never finishes. This affects historical attachments and newly uploaded attachments. Uploading succeeds, and the attachment list (file names and sizes) loads correctly.

Technical details

  • Every attachment request returns HTTP 400, for example:
    GET https://prod-play.zephyr4jiracloud.com/connect/public/rest/api/1.0/attachment/1197d777-ae2e-401e-9889-99ceaf546779/thumbnail?acpt=…&projectId=10356&issueId=1972066
    at 2026-11-03 15:58:53 GMT
  • Response body:

{“errorType”:“ERROR”,“clientMessage”:“We encountered some problems during processing this request. Please try again!”,“errorCode”:134}

Example
Project ID 10356, issue EPS-1165 (ID 1972066), cycle “Q-update 26C”, folder “Procurement”, execution executed 10 Aug 2026. Step attachments such as image_20797.png (0.19 MB) and image_84101.png (0.17 MB).

Impact
These attachments are required evidence for an ongoing audit. Teams cannot retrieve past test evidence.

Questions

  1. Is this a known issue, for example for sites still on app version 9.2.0? Will updating to 12.0.0 fix it?
  2. Are there known issues or steps we need to take when updating from 9.2.0 to 12.0.0?

Kind regards,
Akash Kishore – Jira Admin, KPN