Fix: The entity type 'X' requires a primary key to be defined in EF Core 11
EF Core can't find a key for your type. Either name a property Id or {Type}Id, add [Key], call HasKey, or - if it is a view or raw SQL result - call HasNoKey.
Tag: csharp
187 posts · Page 1 of 19
LINQ Gets FullJoin and Selector-Free Joins in .NET 11 Preview 5
.NET 11 Preview 5 adds a brand-new FullJoin operator to LINQ plus tuple-returning overloads for Join, LeftJoin, RightJoin, and GroupJoin that drop the result selector entirely.
Blazor static SSR forms get client-side validation in .NET 11 Preview 5
Static server-rendered Blazor forms could only validate after a full POST round-trip. .NET 11 Preview 5 renders validation metadata so the Blazor JS enforces DataAnnotations rules in the browser, no circuit required.
Fix: The configured execution strategy 'SqlServerRetryingExecutionStrategy' does not support user-initiated transactions
EnableRetryOnFailure conflicts with BeginTransaction. Wrap the whole transaction in db.Database.CreateExecutionStrategy().ExecuteAsync(...) so it retries as one unit.
System.Text.Json Finally Writes JSON Lines in .NET 11 Preview 5
.NET 11 Preview 5 adds JsonSerializer.SerializeAsyncEnumerable with topLevelValues: true, so System.Text.Json can now stream JSONL out, not just read it.
How to persist state across the Blazor static-to-interactive render boundary in .NET 11
A prerendered Blazor component runs its initialization twice and loses state at the interactive handoff. Fix it with the [PersistentState] attribute or the PersistentComponentState service in .NET 11.
Anthropic SDK vs Microsoft.Extensions.AI for Calling Claude From .NET
Two ways to call Claude from C#: the official Anthropic .NET SDK directly, or the provider-neutral Microsoft.Extensions.AI IChatClient that wraps it. When each wins, what you lose at the abstraction boundary, and why it is not actually either/or. With claude-opus-4-8 and claude-sonnet-4-6 examples.
How to expose OpenAPI without Swashbuckle in ASP.NET Core 11
Swashbuckle is gone from the ASP.NET Core templates. Here is how to generate and serve an OpenAPI document in .NET 11 with the built-in Microsoft.AspNetCore.OpenApi package: AddOpenApi, MapOpenApi, transformers, multiple documents, build-time generation, and a UI on top.
How to use EF Core 11 interceptors for auditing
Stamp CreatedBy/ModifiedOn columns and write a full change-trail with an ISaveChangesInterceptor in EF Core 11, including the DI lifetime, current-user, and ExecuteUpdate gotchas.
GitHub Copilot SDK Hits GA: Embed Copilot's Agent Runtime in Your Own C# Apps
At Build 2026 GitHub shipped Copilot SDK 1.0 GA with a first-class .NET package. You can now drive the same planning, tool-calling, and multi-turn agent runtime from C# code, BYOK included.