instance of entity type cannot be tracked because another instance with same key value is tracked

Question

I\'m using generic repository pattern in asp.net core 2.0 which can not dispose repository object, when I am going to update the entry its updated for one time successfully but

Answer 1

Your DB Context is being shared by multiple requests, meaning that the entity you're editing has been tracked already.

This is likely because your repository service is a Singleton rather than Scoped, and so your DB Context is being reused with the entity being tracked when it's pulled out, and then put back in to the same instance of the DB Context.

What you should be doing instead is having a Scoped Repository, which means that a new instance will be created for each request. Likewise, you will also have a per-request DB Context.

When you register your service it will be using services.AddSingleton<..>

Change this to services.AddScoped<..>, when you inject it into your controller you will then get a new instance per request and your updates should work fine.