Backoffice my settings throws exception if fallbackBehaviour is without Echo


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:


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

Edited, Aug 26, 2019 12:14
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