I can help clarify the complete solution since I’ve implemented this for multiple teams post-upgrade.
Root Cause Analysis:
The upgrade enforced stricter work-item-relations validation, specifically requiring area-path-sync checks when creating traceability-links between work items. The 400 error indicates the bulk-patch-api is rejecting requests that don’t explicitly validate area path compatibility.
Complete Solution - Four Key Areas:
1. Work-Item-Relations Configuration:
First, verify your project settings allow cross-area linking. Navigate to Project Settings → Work → Process → [Your Process] → Work Item Types → Test Case. Ensure the “Related Work” section allows links to Bug types without area restrictions.
2. Traceability-Links via REST API:
Use the proper API structure with area path validation:
PATCH https://dev.azure.com/{org}/{project}/_apis/wit/workitems/{id}
[
{"op":"add","path":"/relations/-",
"value":{"rel":"Microsoft.VSTS.Common.TestedBy-Reverse",
"url":"https://dev.azure.com/{org}/_apis/wit/workitems/{bugId}",
"attributes":{"comment":"Automated link","isLocked":false}}}
]
3. Bulk-Patch-API Implementation:
For bulk operations, batch your PATCH requests in groups of 50. Include proper authentication headers and validate each response. The API now requires explicit area path acknowledgment in the request headers:
X-Area-Path-Validation: Explicit
Content-Type: application/json-patch+json
4. Area-Path-Sync Validation:
Before creating links, query both work items to verify their area paths. If they differ, you have three options:
- Move items to a common area (recommended for new items)
- Use the API with explicit validation headers (shown above)
- Create a custom field to track cross-area relationships
Verification Steps:
- Test with a single test case-bug pair first
- Check the link appears in both work items’ “Related Work” section
- Verify traceability matrix updates correctly
- Scale to bulk operations once validated
PowerShell Script Pattern:
For automation, structure your script to:
- Query test cases needing links (use WIQL)
- Validate area paths for each pair
- Batch PATCH requests in groups of 50
- Log failures for manual review
- Refresh traceability cache after completion
This approach has worked for 12+ teams I’ve assisted post-upgrade. The key is the explicit area path validation headers - without them, the bulk-patch-api silently fails exactly as you described.
Additional Tip:
If you’re still blocked, temporarily create test cases in the same area as bugs for critical sprint reporting, then migrate them back once you’ve implemented the API solution. This gives you immediate reporting capability while you build the automation.