Aaron Bertrand shares some lessons learned:
We recently upgraded multiple systems to SQL Server 2025. The engine upgrade itself was smooth, but three unexpected issues surfaced in our lower environments as we planned out production. None of these issues prevented the upgrade from completing, but all three could easily derail an otherwise smooth in-place upgrade to SQL Server 2025. What were these issues, and how can you avoid hitting them?
My biggest surprise out of this is that full-text search actually got upgraded.