FedEx REST Migration Testing Crisis: Why 67% of Sandbox-Verified Integrations Fail in Production and How to Build Test Harnesses That Actually Predict Real-World Behavior
The FedEx SOAP retirement deadline isn't just another API deprecation. Compatible providers must complete upgrades by March 31, 2026, while customers face a hard June 1, 2026 cutoff. Yet internal testing data from integration teams shows a disturbing pattern: 73% report production authentication failures within weeks of going