Please help with this error: Encountered while using umbraco in backoffice.

Error in developer tool, Get https://localhost:1234/umbraco/backoffice/UmbracoApi/Authentication/Getremainingtimeoutseconds 500 (internal server error )

Logs: [P9300/D2/T13] ERROR Umbraco.Core.UmbracoApplicationBase - An unhandled exception occurred

System.ArgumentException: The key 'Pragma' is already present in the dictionary.

at Microsoft.Owin.Host.SystemWeb.CallHeaders.AspNetResponseHeaders.Add(String key, String[] value)

at Microsoft.Owin.HeaderDictionary.Add(String key, String[] value)

at Umbraco.Web.Security.Identity.GetUserSecondsMiddleWare.

--- 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 Umbraco.Web.Security.Identity.FixWindowsAuthMiddlware.

--- 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 Microsoft.Owin.Security.Infrastructure.AuthenticationMiddleware`1.

--- 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 Microsoft.Owin.Security.Infrastructure.AuthenticationMiddleware`1.

--- 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 Microsoft.AspNet.Identity.Owin.IdentityFactoryMiddleware`2.

--- 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 Microsoft.AspNet.Identity.Owin.IdentityFactoryMiddleware`2.

--- 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 Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.IntegratedPipelineContextStage.

--- 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 Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.IntegratedPipelineContext.

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

at Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.StageAsyncResult.End(IAsyncResult ar)

at Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.IntegratedPipelineContext.EndFinalWork(IAsyncResult ar)

at System.Web.HttpApplication.AsyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()

at System.Web.HttpApplication.ExecuteStepImpl(IExecutionStep step)

at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)