Upgrade Possibility!

Hi ​@Jupiter ,

API/Integration Changes:
- As you noted, URL-encoded authentication is removed in 2026R1 — you'll need OAuth 2.0 or token-based auth
- Contract-based API versioning changes — check your endpoint versions are still supported
- Some REST API endpoints may have schema changes
Customization Framework:
- DAC field changes (fields renamed, moved, or removed between versions)
- Graph/BLC class restructuring — if your customizations override methods, the signatures may change
- Workflow engine changes (2024R1+ introduced significant workflow updates)
- Obsolete attributes and APIs that were deprecated and then removed
Recommended Approach
1. Compile-test each version step — Even if upgrading sequentially, publish your customization package at each intermediate version in a test environment and check for compilation errors first.
2. Use the Customization Validation tool — Acumatica has a built-in validator that flags broken references when you publish.
3. GIs are generally safe — Generic Inquiries rarely break unless the underlying DAC/fields were renamed or removed. You'll get clear errors on publish.
4. Business Events — These can break if the triggering conditions reference fields/screens that changed. Test each one.
5. Review release notes for each intermediate version — Acumatica publishes "Breaking Changes" sections in their release notes. Pay special attention to:
   - 2024R1 (workflow engine overhaul)
   - 2025R1 (further API deprecations)
   - 2026R1 (auth changes you already identified)
6. Export your customization packages as XML and diff them after re-publishing on the new version to see what auto-adjusted vs what broke.
Practical Tips
- Stand up a parallel test instance for each version hop
- Automate regression testing of your APIs (Postman collections or similar)
- Prioritize fixing compilation errors, then functional testing
- If you have custom code referencing internal/non-public APIs, those are the highest risk

Hope above helps !!

HI ​@Jupiter 

Along with the previous post, ensure you have a sandbox to test everything with the version you plan to use, I would suggest a separate sandbox which you can get from Acumatica.