Error opening Design Studio

Hi,
I tried to access the Design Studio and encountered this error.
Has anyone encountered this problem before?

Thank you,
Raluca

Type: System.Exception
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Message: Value cannot be null.

Parameter name: id
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CallStack
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at WebCon.WorkFlow.Base.Exceptions.Handling.ExceptionHandler.ThrowException(Error error)

at WebCon.WorkFlow.Studio.Logic.Authentication.PortalRequestHandler.CreateException(HttpResponseMessage response)

at WebCon.WorkFlow.Studio.Logic.Authentication.PortalRequestHandler.ExecuteGetRequest(String path)

at WebCon.WorkFlow.Studio.Logic.PortalService.PortalService.GetUserByBpsId(String id)

at WebCon.WorkFlow.Studio.Logic.Managers.PermissionsManager.ConvertLoginIntoPermission(String login)

at System.Linq.Enumerable.WhereSelectArrayIterator`2.MoveNext()

at WebCon.WorkFlow.Studio.Logic.Managers.BasePermissionsManager.FillPermisionsCollection(String permissionString, IPermissionsCollection collectionToFill, ConvertIntoPermission convertIntoPermission)

at WebCon.WorkFlow.Studio.Logic.Managers.ProcessTreeStructureDownloader.FillApplication(ApplicationEntity applicationEntity, IEnumerable`1 processes, IEnumerable`1 permissions, IEnumerable`1 dashboards, IEnumerable`1 linkedProcesses, IEnumerable`1 starts, IEnumerable`1 reports)

at WebCon.WorkFlow.Studio.Logic.Managers.ProcessTreeStructureDownloader.GetApplicationGroupsStructure()

at WebCon.WorkFlow.Studio.Forms.ModuleProcess.ProcessController.RefreshData()

at WebCon.WorkFlow.Studio.Forms.ModuleProcess.ProcessPanel.RaiseDataRefreshRequest()

at WebCon.WorkFlow.Studio.Forms.ModuleProcess.ProcessPanel.ModulesPanel_Load(Object sender, EventArgs e)

at System.EventHandler.Invoke(Object sender, EventArgs e)

at System.Windows.Forms.UserControl.OnLoad(EventArgs e)

at DevExpress.XtraEditors.XtraUserControl.OnLoad(EventArgs e)

at System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible)

at System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible)

at System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible)

at System.Windows.Forms.Control.CreateControl()

at System.Windows.Forms.Control.SetVisibleCore(Boolean value)

at DevExpress.XtraNavBar.NavBarGroup.SetControlContainerVisibility(Boolean visible)

at DevExpress.XtraNavBar.NavBarGroup.UpdateControlContainer(Rectangle clientBounds)

at DevExpress.XtraNavBar.ViewInfo.NavBarViewInfo.UpdateGroupBounds()

at DevExpress.XtraNavBar.ViewInfo.NavBarViewInfo.Calc(Rectangle bounds)

at DevExpress.XtraNavBar.NavBarControl.CheckViewInfo()

at DevExpress.XtraNavBar.NavBarControl.OnPaint(PaintEventArgs e)

at System.Windows.Forms.Control.PaintWithErrorHandling(PaintEventArgs e, Int16 layer)

at System.Windows.Forms.Control.WmPaint(Message& m)

at System.Windows.Forms.Control.WndProc(Message& m)

at DevExpress.XtraNavBar.NavBarControl.WndProc(Message& m)

at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
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