What does the following error mean and how to resolve it?
The call is ambiguous between the following methods or properties: 'System.Security.Claims.PrincipalExtensions.FindFirstValue(System.Security.Claims.ClaimsPrincipal, string)' and 'System.Security.Claims.PrincipalExtensions.FindFirstValue(System.Security.Claims.ClaimsPrincipal, string)'
You have an very old dependency on
Microsoft.AspNet.Identity.EntityFramework. It is pulling all the old pre-rc2 packages in your solution and you end up with two assemblies with different name and different versions and compiler doesn't know which one to choose.
Together with ASP.NET Core
Microsoft.AspNet.Identity.EntityFramework was renamed to
Microsoft.AspNetCore.Identity.EntityFrameworkCore (notice the Core part) and its version should be 1.1.0 too with the rest of your ASP.NET Core packages.
Be careful when following very old tutorials (ones which refer
Microsoft.EntityFramework.* packages or ones that are older than July 2016) as they are based on the framework before the assemblies got renamed.