Start Debugging

Tag: csharp

321 posts · Page 12 of 33

2026-06-26 errors csharp dotnet

Fix: FOREIGN KEY constraint failed when deleting an entity in EF Core 11

EF Core throws FOREIGN KEY constraint failed because the parent still has dependents the database refuses to orphan. Load the children, make the relationship optional, or configure OnDelete.

2026-06-26 errors csharp dotnet

Fix: No service for type 'Microsoft.EntityFrameworkCore.DbContextOptions' has been registered

EF Core throws this when AddDbContext never ran, ran after Build, or your context's constructor takes the wrong DbContextOptions. Register before Build and use DbContextOptions<YourContext>.

2026-06-25 errors csharp dotnet

Fix: 405 Method Not Allowed instead of 401 with JWT bearer in ASP.NET Core

A protected endpoint returning 405 instead of 401 almost always means routing rejected the HTTP verb before auth ran, or a cookie scheme stole the challenge. Here is how to tell which.

2026-06-25 csharp dotnet dotnet-11

Why your ASP.NET Core JWT returns 401 even with a valid token

A valid token that still 401s almost always means the bearer handler never ran or ran under the wrong scheme. Check middleware order, the default scheme, the scheme name, and whether the header even reached the handler.

2026-06-25 errors csharp dotnet

Fix: The seed entity for entity type 'X' cannot be added because a non-zero value is required for property 'Id'

HasData seeds an entity with a store-generated key but no explicit value. Give every seed row a stable non-zero Id, or switch to UseSeeding for generated keys.

2026-06-24 how-to csharp csharp-14

How to declare extension properties in C# 14

Extension properties land in C# 14 through the new extension block. Declare get-only, settable, static, and generic extension properties, why auto-properties are rejected, and how the compiler lowers them to get_/set_ accessors.

2026-06-23 microsoft-agent-framework ai-agents azure-ai-foundry

How to Deploy a Microsoft Agent Framework Agent to Foundry Hosted Agents

A step-by-step guide to taking a Microsoft Agent Framework agent from your laptop to a managed Foundry Hosted Agent: the C# host code, the azd deploy flow, identity, scaling, and the gotchas that bite in preview.

2026-06-23 how-to ef-core ef-core-11

How to do keyset (cursor) pagination in EF Core 11

Replace Skip/Take with a WHERE clause that seeks past the last row you saw. Order by a fully unique key, carry the last row's values as a cursor, and EF Core 11 turns the next page into an index seek instead of an OFFSET scan.

2026-06-23 csharp dotnet dotnet-11

How to register and resolve keyed services in .NET 11 dependency injection

Register more than one implementation of the same interface under a key with AddKeyedSingleton/Scoped/Transient, then resolve them with [FromKeyedServices], GetRequiredKeyedService, or KeyedService.AnyKey. The keyed and non-keyed registries are separate, which is the gotcha that bites most people.

2026-06-22 csharp dotnet dotnet-11

How to validate a JWT's issuer, audience, and lifetime in ASP.NET Core 11

A complete guide to TokenValidationParameters in ASP.NET Core 11: how ValidateIssuer, ValidateAudience, and ValidateLifetime work, what the defaults actually are, why Authority auto-configures the issuer and signing keys, the 5-minute ClockSkew trap, and how to read the IDX error codes when a valid-looking token is rejected.