Based on the discussion here, let me share our complete migration strategy for large pol-2310 upgrades that addresses all the concerns raised:
Baseline Export/Import Considerations
For 500+ projects, baseline export/import is not your best option despite being simpler conceptually. The export process will struggle with memory allocation and you risk partial exports that corrupt your data. We attempted this approach initially and abandoned it after the third failed export attempt. Baseline export works well for under 100 projects but doesn’t scale to enterprise installations.
Pre-Upgrade Analyzer Deep Dive
Run the pre-upgrade analyzer three times during your planning phase: initial assessment, after fixing critical issues, and final validation before cutover. Pay special attention to custom workflow warnings - these almost always indicate breaking changes in pol-2310. Document every flagged workflow extension and test each one individually on your parallel instance. We found that 30% of our custom workflows needed code updates for pol-2310 compatibility.
Parallel Instance Sync Architecture
This is your best path forward for 500 projects. Set up a complete pol-2310 instance in parallel with your production pol-2203 system. Use Polarion’s built-in sync tools to replicate data incrementally - start with project structure and configuration, then sync work items in batches of 10,000 items. Run continuous sync for 2-3 weeks before cutover so you can identify and fix data inconsistencies early. The parallel approach lets teams test the new version while production stays operational.
Read-Only Cutover Strategy
This is the critical piece that ensures data integrity. Schedule your cutover for a sprint boundary - ideally the Friday before sprint planning week. Put the production pol-2203 instance in read-only mode 48 hours before final sync. During read-only period: teams can view backlogs, generate reports, and review sprint progress, but cannot create or modify work items. This freeze window prevents sync conflicts and gives you a stable snapshot to migrate.
Sprint Boundary Timing Coordination
Coordinate with all 40+ teams to align their sprint closures within a two-week window. This doesn’t mean freezing all work, but rather scheduling the upgrade during the natural sprint break when teams are doing retrospectives and planning. We sent a migration timeline to all scrum masters six weeks before cutover with specific dates for read-only mode, cutover execution, and production validation. Most teams appreciated the advance notice and adjusted their sprint schedules accordingly.
Final Cutover Execution
With 320 projects our final cutover took 14 hours including validation. For 500 projects expect 18-22 hours. Run the final sync overnight, validate data integrity with automated scripts, then open pol-2310 for production use. Keep the pol-2203 instance available in read-only mode for 1-2 weeks as a fallback reference. We didn’t need to rollback but having that safety net gave stakeholders confidence.
The parallel instance sync method with sprint boundary timing gave us zero data loss and minimal disruption. The key is starting the parallel sync early and running it continuously so you’re not trying to migrate 500 projects in a single cutover window.