Unhandled web exception when performing mailbox assignment - The required anti-forgery form field "__RequestVerificationToken" is not present (4381238)

After upgrading to 5.10, facing unhandled exception when navigating to the web administration page > Mailbox Assignment > [...]

[HttpAntiForgeryException (0x80004005): The required anti-forgery form field "__RequestVerificationToken" is not present.]
System.Web.Helpers.AntiXsrf.TokenValidator.ValidateTokens(HttpContextBase httpContext, IIdentity identity, AntiForgeryToken sessionToken, AntiForgeryToken fieldToken) +483
System.Web.Helpers.AntiXsrf.AntiForgeryWorker.Validate(HttpContextBase httpContext) +71
System.Web.Helpers.AntiForgery.Validate() +92
Quest.AM.Website.Controls.LoginSearch.Page_Load(Object sender, EventArgs e) +37
System.Web.UI.Control.OnLoad(EventArgs e) +97
System.Web.UI.Control.LoadRecursive() +61
System.Web.UI.Control.LoadRecursive() +134
System.Web.UI.Control.LoadRecursive() +134
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +693

This issue is caused by a defect in the Quest.AM.Website.dll file included with version 5.10.
The affected DLL does not properly generate or handle the required anti-forgery token during page load, resulting in the ASP.NET runtime throwing an HttpAntiForgeryException.

In essence, the web component responsible for validating user form submissions fails due to missing anti-forgery token handling logic introduced in this build.

1. Stop all AM Services
2. Back up Quest.AM.Website.dll 
3. Replace the dll in the installation folder, For example path : C:\Program Files (x86)\Quest\Archive Manager\WebSite\bin
4. Restart AM Services