InvalidOperationException: sub claim is missing on logout

I'm getting error on logout in the following line:

var subjectId = HttpContext.User.Identity.
GetSubjectId();

InvalidOperationException: sub claim is missing
IdentityServer4.Extensions .PrincipalExtensions. GetSubjectId(IIdentity identity)
IdentityServer.Controllers. Account.AccountController+<Logout>d__17.MoveNext() in AccountController.cs
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
System.Runtime.CompilerServices.TaskAwaiter.GetResult()
IdentityServer.Controllers.Account.AccountController+<Logout>d__16.MoveNext() in AccountController.cs
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
System.Runtime.CompilerServices.TaskAwaiter.GetResult()
Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker+<InvokeActionMethodAsync>d__12.MoveNext()
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
System.Runtime.CompilerServices.TaskAwaiter.GetResult()
Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker+<InvokeNextActionFilterAsync>d__10.MoveNext()