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Tag: dotnet

284 posts · Page 2 of 29

2026-07-17 errors csharp dotnet

Fix: System.InvalidOperationException: Headers are read-only, response has already started

You set a header, status code, or content type after the body was already flushed. Set all headers before the first write, or guard with HttpResponse.HasStarted and OnStarting.

2026-07-17 errors csharp dotnet

Fix: "The property could not be mapped, because it is not a supported primitive type or a valid entity type" in EF Core 11

EF Core hit a property it does not know how to store. Map it as a complex type, convert it with HasConversion, give it a key, or ignore it with [NotMapped].

2026-07-14 csharp dotnet dotnet-11

How to add response compression to an ASP.NET Core 11 API

A complete guide to response compression in ASP.NET Core 11: AddResponseCompression and UseResponseCompression, the new built-in Zstandard provider alongside Brotli and Gzip, compression levels, EnableForHttps and the CRIME/BREACH risk, custom MIME types, middleware ordering, and when to let the reverse proxy do it instead.

2026-07-14 csharp dotnet dotnet-11

How to return a typed Results<T1, T2> union from a minimal API endpoint in ASP.NET Core 11

Declare the handler's return type as Results<Ok<T>, NotFound> and return TypedResults.Ok / TypedResults.NotFound: the union gives compile-time checking that the handler only returns what it declares, and it self-describes to OpenAPI so you never write .Produces by hand. Covers async handlers, the six-type limit, and testing in ASP.NET Core 11.

2026-07-12 csharp dotnet dotnet-11

How to add output caching to a minimal API in ASP.NET Core 11

A complete, working guide to output caching in an ASP.NET Core 11 minimal API: AddOutputCache and UseOutputCache, CacheOutput on endpoints and MapGroup, named and base policies, Expire, VaryByQuery and VaryByHeader, tag-based eviction with EvictByTagAsync, cache stampede protection, ETag revalidation, and a Redis backing store.

2026-07-12 csharp dotnet dotnet-11

How to customize the OpenAPI document with AddOperationTransformer and AddSchemaTransformer in ASP.NET Core 11

A deep dive into the built-in OpenAPI transformer pipeline in .NET 11: operation vs schema transformers, the context objects, execution order, DI-activated transformers, and recipes for headers, responses, examples, and per-property tweaks.

2026-07-11 dotnet performance jit

What is PGO in .NET and do I need to opt in?

PGO (profile-guided optimization) lets the .NET JIT specialize hot code for the types and branches your workload actually hits. Dynamic PGO has been on by default since .NET 8, so on .NET 8 and later you do not need to opt in. Here is what it does, how to see its effect, and the rare cases where you touch the knob.

2026-07-11 dotnet performance jit

What is tiered compilation and how do I reason about it?

Tiered compilation lets the .NET JIT compile every method twice: once fast and unoptimized to get your app running, then again with full optimizations once the runtime knows a method is hot. Here is how tier 0, tier 1, on-stack replacement, and Dynamic PGO fit together, and how to observe and tune them.

2026-07-10 dotnet github-copilot ai-agents

The .NET Modernization Agent Now Runs in the Copilot CLI, Not Just Visual Studio

GitHub Copilot's modernize-dotnet agent shipped as a portable plugin on July 9, 2026. It now runs in VS Code, the Copilot CLI, and on GitHub, with an assess to plan to execute workflow whose artifacts get committed to your repo for review.

2026-07-10 dotnet dotnet-cli msbuild

What is the difference between dotnet build and dotnet publish?

dotnet build compiles your project for the inner development loop and defaults to Debug. dotnet publish runs the MSBuild Publish target, defaults to Release on net8.0 and later, and packages a deployable folder with web assets, self-contained runtimes, single-file, trimming, and AOT handled. Here is exactly what each one produces and when to reach for it.