Asp.net does not allow more than one user logged in

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ASP.NET

authentication

IIS8

OWIN

, +

Hello,

I have 2 applications running on IIS 8.5. Both of the applications need authentication. For the Authentication I used the Identity Data Model. When I run the applications from the debugger I have no problem login more than one user at the time.

When I take them to the IIS the applications don't allow more that one user at the time and they keep redirect users to login page (no error message). If I restart the IIS the applications allow multiusers for a while and then they don't.

I'm using .NET framework 4.5.2

I'm getting this warning on server's event viewer:

Exception information: 
    Exception type: HttpException 
    Exception message: Server cannot append header after HTTP headers have been sent.
   at System.Web.HttpHeaderCollection.SetHeader(String name, String value, Boolean replace)
   at System.Web.HttpHeaderCollection.Set(String name, String value)
   at Microsoft.Owin.Host.SystemWeb.CallHeaders.AspNetResponseHeaders.Set(String key, String[] values)
   at Microsoft.Owin.Host.SystemWeb.CallHeaders.AspNetResponseHeaders.set_Item(String key, String[] value)
   at Microsoft.Owin.Infrastructure.OwinHelpers.SetHeaderUnmodified(IDictionary`2 headers, String key, String[] values)
   at Microsoft.Owin.Infrastructure.OwinHelpers.AppendHeaderUnmodified(IDictionary`2 headers, String key, String[] values)
   at Microsoft.Owin.HeaderDictionary.AppendValues(String key, String[] values)
   at Microsoft.Owin.Infrastructure.ChunkingCookieManager.AppendResponseCookie(IOwinContext context, String key, String value, CookieOptions options)
   at Microsoft.Owin.Security.Cookies.CookieAuthenticationHandler.<ApplyResponseGrantAsync>d__f.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 Microsoft.Owin.Security.Infrastructure.AuthenticationHandler.<ApplyResponseCoreAsync>d__b.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 Microsoft.Owin.Security.Infrastructure.AuthenticationHandler.<ApplyResponseAsync>d__8.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 Microsoft.Owin.Security.Infrastructure.AuthenticationHandler.<TeardownAsync>d__5.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 Microsoft.Owin.Security.Infrastructure.AuthenticationMiddleware`1.<Invoke>d__0.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 Microsoft.AspNet.Identity.Owin.IdentityFactoryMiddleware`2.<Invoke>d__0.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 Microsoft.AspNet.Identity.Owin.IdentityFactoryMiddleware`2.<Invoke>d__0.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 Microsoft.AspNet.Identity.Owin.IdentityFactoryMiddleware`2.<Invoke>d__0.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 Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.IntegratedPipelineContextStage.<RunApp>d__5.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 Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.IntegratedPipelineContext.<DoFinalWork>d__2.MoveNext()
--- 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.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

Any kind of help would be appreciated.

Thank you in advance.

What I have tried:

1. Checked the code for errors
2. Restarted IIS
3. Restarted the server (Windows Server 2012 R2)
4. Upgraded OWIN but OWIN Cookies 3.1 didn't work so I downgraded it again to 3.0.1