When you impersonate a user and then try to re-impersonate your own user account, the Impersonate User popup window shows an error Failed API level ACL ValidationDescription<!-- div.margin{ padding: 10px 40px 40px 30px; } table.tocTable{ border: 1px solid; border-color:#E0E0E0; background-color: rgb(245, 245, 245); padding-top: .6em; padding-bottom: .6em; padding-left: .9em; padding-right: .6em; } table.noteTable{ border:1px solid; border-color:#E0E0E0; background-color: rgb(245, 245, 245); width: 100%; border-spacing:2; } table.internaltable { white-space:nowrap; text-align:left; border-width: 1px; border-collapse: collapse; font-size:14px; width: 85%; } table.internaltable th { border-width: 1px; padding: 5px; border-style: solid; border-color: rgb(245, 245, 245); background-color: rgb(245, 245, 245); } table.internaltable td { border-width: 1px; padding: 5px; border-style: solid; border-color: #E0E0E0; color: #000000; } .title { color: #D1232B; font-weight:normal; font-size:28px; } h1{ color: #D1232B; font-weight:normal; font-size:21px; margin-bottom:-5px } h2{ color: #646464; font-weight:bold; font-size:18px; } h3{ color: #000000; font-weight:BOLD; font-size:16px; text-decoration:underline; } h4{ color: #646464; font-weight:BOLD; font-size:15px; text-decoration:; } h5{ color: #000000; font-weight:BOLD; font-size:13px; text-decoration:; } h6{ color: #000000; font-weight:BOLD; font-size:14px; text-decoration:; } ul{ list-style: disc outside none; margin-left: 0; } li { padding-left: 1em; } --> Symptoms When you impersonate a user and then try to re-impersonate your own user account, the Impersonate User popup window shows an error Failed API level ACL Validation Release All releases. Cause Missing a required role, snc_internal, for the RESTAPIProcessor Access Control (ACL) record. Resolution 1. Go to System Security > Access Control (ACL) 2. Filter for Name is RESTAPIProcessor 3. Open the matching record 4. Under the Requires Role related list, if you see a role that has a blank Sys user role, double click the blank value and in the suggestions popup, find and select the snc_internal role. Click the green checkmark to save the change. 5. Save the ACL record. After performing these steps, you should be able to impersonate other users and re-impersonate yourself without getting the error.