The Role Manager feature has not been enabled

Question

You can do this by reading from the boolean property at:

System.Web.Security.Roles.Enabled

This is a direct read from the enabled attribute of the roleManager element in the web.config:

<configuration>
  <system.web>
    <roleManager enabled="true" />
  </system.web>
</configuration>

Update:
For more information, check out this MSDN sample: https://msdn.microsoft.com/en-us/library/aa354509(v=vs.110).aspx

If you got here because you're using the new ASP.NET Identity UserManager, what you're actually looking for is the RoleManager:

var roleManager = new RoleManager<IdentityRole>(new RoleStore<IdentityRole>(new ApplicationDbContext()));

roleManager will give you access to see if the role exists, create, etc, plus it is created for the UserManager

I found 2 suggestions elsewhere via Google that suggested a) making sure your db connectionstring (the one that Roles is using) is correct and that the key to it is spelled correctly, and b) that the Enabled flag on RoleManager is set to true. Hope one of those helps. It did for me.

Did you try checking Roles.Enabled? Also, you can check Roles.Providers to see how many providers are available and you can check the Roles.Provider for the default provider. If it is null then there isn't one.

I found this question due the exception mentioned in it. My Web.Config didn't have any <roleManager> tag. I realized that even if I added it (as Infotekka suggested), it ended up in a Database exception. After following the suggestions in the other answers in here, none fully solved the problem.

Since these Web.Config tags can be automatically generated, it felt wrong to solve it by manually adding them. If you are in a similar case, undo all the changes you made to Web.Config and in Visual Studio:

1. Press Ctrl+Q, type nuget and click on "Manage NuGet Packages";
2. Press Ctrl+E, type providers and in the list it should show up "Microsoft ASP.NET Universal Providers Core Libraries" and "Microsoft ASP.NET Universal Providers for LocalDB" (both created by Microsoft);
3. Click on the Install button in both of them and close the NuGet window;

4. Check your Web.config and now you should have at least one <providers> tag inside Profile, Membership, SessionState tags and also inside the new RoleManager tag, like this:

   <roleManager defaultProvider="DefaultRoleProvider">
       <providers>
          <add name="DefaultRoleProvider" type="System.Web.Providers.DefaultRoleProvider, System.Web.Providers, Version=2.0.0.0, Culture=neutral, PublicKeyToken=NUMBER" connectionStringName="DefaultConnection" applicationName="/" />
       </providers>
   </roleManager>
   

5. Add enabled="true" like so:

   <roleManager defaultProvider="DefaultRoleProvider" enabled="true">
   

6. Press F6 to Build and now it should be OK to proceed to a database update without having that exception:

   1. Press Ctrl+Q, type manager, click on "Package Manager Console";
   2. Type update-database -verbose and the Seed method will run just fine (if you haven't messed elsewhere) and create a few tables in your Database;
   3. Press Ctrl+W+L to open the Server Explorer and you should be able to check in Data Connections > DefaultConnection > Tables the Roles and UsersInRoles tables among the newly created tables!

If you are using ASP.NET Identity UserManager you can get it like this as well:

var userManager = Request.GetOwinContext().GetUserManager<ApplicationUserManager>();

var roles = userManager.GetRoles(User.Identity.GetUserId());

If you have changed key for user from Guid to Int for example use this code:

var roles = userManager.GetRoles(User.Identity.GetUserId<int>());