UI16: Unable to impersonate user if sys_user_preference for m_sort (mobile sort) is using invalid sort fieldDescription UI16: Unable to impersonate user if sys_user_preference for m_sort (mobile sort) is using invalid sort field Steps to Reproduce Navigate to User Administration > Users. Change the view to Mobile. /nav_to.do?uri=/sys_user_list.do%3Fsysparm_view/Mobile&sysparm_userpref.sys_user_list.view/Mobile&sysparm_userpref.sys_user.view/Mobile&sysparm_query/&sysparm_fixed_query/ Right-click the Name column and choose Configure > List Layout. Add Last Name and click Save. Impersonate Fred Luddy. Navigate to Mobile > User Administration > Users. $m.do#/!list/sys_user Change sort to 'Last name', ascending. In sys_user_preference, a new record for Fred Luddy is created with Name=m_sort: nav_to.do?uri=sys_user_preference.do?sys_id=9ec3d4f613fe12003c4ebdb12244b028 It will have the following value: {"l_s_sys_user":"last_name,ascending"} Go back to Mobile view for User [sys_user] and remove Last name from the list layout. nav_to.do?uri=/sys_user_list.do%3Fsysparm_view/Mobile&sysparm_userpref.sys_user_list.view/Mobile&sysparm_userpref.sys_user.view/Mobile&sysparm_query/&sysparm_fixed_query/ Right-click the Name column and choose Configure > List Layout. Remove Last Name and click Save. Still as Fred Luddy, choose Impersonate User and click into the Search for user field. You cannot type the name of a user in the field due to the invalid sort field. Workaround This issue can be solve in either of the following two ways: Add the invalid sort field back to the mobile list.Sort the mobile list by a valid field. Related Problem: PRB671119