How to Handle Graceful Degradation Without Leaving Protected Routes Broken

A recent software change highlighted a subtle but critical flaw in how web applications handle graceful degradation when dependencies are missing. In an ASP.NET Core application with both public and protected routes, removing a database dependency did not automatically satisfy the framework's authentication and authorization contracts, causing a protected endpoint to throw a 500 error instead of failing safely. The root cause was that a fallback middleware intercepted a nearby URL correctly but missed the actual protected route, which the framework processed through its security pipeline before the fallback could respond. The fix involved registering an explicit 'unavailable' authentication scheme when the identity store is absent, keeping the security pipeline coherent so protected routes challenge or deny access rather than crash. The broader principle is that missing infrastructure should be modeled as a deliberate, supported application state, with separate liveness and readiness probes to accurately reflect which parts of the system are operational.