Fix: HttpClient DelegatingHandler DI Scoped Service Error

The Error

Runtime:

InvalidOperationException: Cannot resolve scoped service from root provider

Quick Fix - 1 Min

1. DelegatingHandler registered as Singleton. Cannot inject Scoped. 2. Inject IServiceProvider and scope = provider.CreateScope(). 3. Or use AddHttpMessageHandler<T>() with Scoped lifetime.

Root Cause

HttpClientFactory creates handler once. Scoped services live per-request.