Hi,

In backoffice when right clicking on the current users name and selecting My settings (or similar, where it is possible to change the language and mine is not English - which I wanted to change :-)), Episerver throws the following exception:

[ArgumentNullException: Value cannot be null.
Parameter name: resourceKey]
   EPiServer.Framework.Localization.LocalizationService.GetStringByCulture(String resourceKey, FallbackBehaviors fallbackBehavior, String fallback, CultureInfo culture) +339
   EPiServer.UI.WebControls.TabStrip.LoadPlugIns() +447
   EPiServer.UI.WebControls.TabStrip.OnInit(EventArgs e) +38
   System.Web.UI.Control.InitRecursive(Control namingContainer) +391
   System.Web.UI.Control.InitRecursive(Control namingContainer) +184
   System.Web.UI.Control.AddedControl(Control control, Int32 index) +204
   System.Web.UI.ControlCollection.Add(Control child) +157
   EPiServer.UI.Edit.MySettings.CreateChildControls() +223
   System.Web.UI.Control.EnsureChildControls() +116
   System.Web.UI.Control.PreRenderRecursiveInternal() +49
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +4716

It happens only if Echo is not there in fallbackBehaviour, my config:

localization fallbackBehavior="FallbackCulture" fallbackCulture="en"

I debugged it through in the LoadPlugins when it is trying to load plugn AssemblyName = "EPiServer.UI" TypeName = "EPiServer.UI.Edit.UserGuiSettings" from AssemblyName = "EPiServer.UI" it fetches the resource /admin/edituser/userguisettings/description once, the system returns an empty string and then for some reason it gets fetched again in LoadPlugins and then comes the ArgumentException. So the code is like this:

LocalizationService.Current.GetString(LocalizationService.Current.GetString("/admin/edituser/userguisettings/description"))

I think the resource should not be fetched like this. Also tried with later Episerver.UI package 11.21.4