“Context cannot be used while the model is being created” exception with ASP.NET Identity

Question

Why is this happening when we make a call to the AccountApiController.Register() method?

what is trying to use the context?
what is trying to create the context?
how do we avoid this?
how do we debug this?

"Message":"An error has occurred.",

"ExceptionMessage":"The context cannot be used while the model is being created. This exception may be thrown if the context is used inside the OnModelCreating method or if the same context instance is accessed by multiple threads concurrently. Note that instance members of DbContext and related classes are not guaranteed to be thread safe.",

"ExceptionType":"System.InvalidOperationException",

"StackTrace":"

at System.Web.Http.ApiController.d__1.MoveNext()

--- End of stack trace from previous location where exception was thrown

at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)

at System.Runtime.CompilerServices.TaskAwaiter .HandleNonSuccessAndDebuggerNotification(Task > task)

at System.Web.Http.Dispatcher.HttpControllerDispatcher.d__0.MoveNext()"

Make sure that you don't use the same context object for different requests and make sure that you send request after OnModelCreating. you can add there breakpoint in end of method. — Daniil Grankin
How do we make sure that we don't use the same context object for different requests? Also, I am not sure what you mean by adding a breakpoint because we don't have an OnModelCreating method. — Shaun Luttin
I've learned that the ASP.NET Identity uses the Factory Pattern in order to get one instance of UserManager per request; this might be a problem, because our UserManager stores data in our DbContext. Hmm. — Shaun Luttin
try to make your methods Async, this might solve the problem — user2982369

Shaun Luttin Shaun Luttin · Accepted Answer · 2014-01-25T03:08:36

The problem was that we were NOT using the factory pattern that MS recommends.

You can use Factory implementation to get an instance of UserManager from the OWIN context. ... This is a recommended way of getting an instance of UserManager per request for the application.

As a result, "the same context instance is accessed by multiple threads concurrently," because several requests and thus threads shared a DbContext.

This following is correct. It creates a new instance of MyDbContext for each call to the UserManagerFactory function.

UserManagerFactory 
= () => new UserManager<IdentityUser>(new UserStore<IdentityUser>(new MyDbContext()));

The following is incorrect. It look similar but does not create a new instance for each call to UserManagerFactory. It is what we were using, ergo our site broke.

var userStore = new UserStore<IdentityUser>(new MyDbContext());                    
var userManager = new UserManager<IdentityUser>(userStore);
UserManagerFactory = () => userManager;

“Context cannot be used while the model is being created” exception with ASP.NET Identity

7 Answers