Intermittent NullReferenceException when Accessing Properties of an Entity Framework DbContext in ASP.NET Core 6
I've encountered a strange issue with I've been working on this all day and I'm running into an intermittent `NullReferenceException` when accessing properties of an entity retrieved from a DbContext in my ASP.NET Core 6 application. The issue seems to occur during a high load, particularly when multiple requests are made simultaneously. Here’s a simplified version of my code: ```csharp public class MyService { private readonly MyDbContext _dbContext; public MyService(MyDbContext dbContext) { _dbContext = dbContext; } public async Task<MyEntity> GetEntityAsync(int id) { var entity = await _dbContext.MyEntities.FindAsync(id); return entity; } } ``` I’m calling `GetEntityAsync` in a controller action: ```csharp [HttpGet("/entity/{id}")] public async Task<IActionResult> GetEntity(int id) { var entity = await _myService.GetEntityAsync(id); if (entity == null) { return NotFound(); } return Ok(entity); } ``` Sometimes, when I get the response back from the API, I get a `NullReferenceException` when trying to access properties of the returned entity, like `entity.SomeProperty`. I’ve added logging, and it appears that the entity is not null; however, it seems to have lost its context. I suspect it may be related to the way the DbContext is being scoped or how Entity Framework handles detached entities under certain conditions. I've tried setting the `DbContext` lifetime to Transient instead of Scoped, but it made the issue worse, causing even more `NullReferenceExceptions`. I also double-checked that I'm not modifying the DbContext from multiple threads. I’m using the following versions: - .NET 6.0 - Microsoft.EntityFrameworkCore 6.0.0 Has anyone faced a similar issue or have insights on how to troubleshoot this? Any suggestions would be appreciated! Is there a simpler solution I'm overlooking? I recently upgraded to C# stable.