The following unhandled exception may occur when using the User Manager application to reset passwords for user accounts stored in membership providers that have the “Enabled Password Reset” and “Requires Question And Answer” functionality enabled.
ArgumentNullException: Value cannot be null. Parameter name: passwordAnswer
Examples of the membership providers that support question and answer are SqlMembershipProvider and ActiveDirectoryMembershipProvider.
Copy the Sitecore.Support.334561.dll file to the /bin folder. This dll contains the password question/answer dialog that appears when you are trying to reset the password for a user.
In the /sitecore/shell/Applications/Security/SetPassword/SetPassword.xaml.xml file, replace the following line:
<Sitecore.Shell.Applications.Security.SetPassword Application="Security/Edit User" x:inherits="Sitecore.Shell.Applications.Security.SetPassword.SetPasswordPage,Sitecore.Client">
with
<Sitecore.Shell.Applications.Security.SetPassword Application="Security/Edit User" x:inherits="Sitecore.Support.Shell.Applications.Security.SetPassword.SetPasswordPage,Sitecore.Support.334561">