diff --git a/services/web/app/src/Features/UserMembership/UserMembershipController.mjs b/services/web/app/src/Features/UserMembership/UserMembershipController.mjs
index 1f2516b0f5..7b632d7569 100644
--- a/services/web/app/src/Features/UserMembership/UserMembershipController.mjs
+++ b/services/web/app/src/Features/UserMembership/UserMembershipController.mjs
@@ -210,7 +210,7 @@ export default {
           return res.status(404).json({
             error: {
               code: 'user_not_found',
-              message: req.i18n.translate('user_not_found'),
+              message: req.i18n.translate('add_manager_user_not_found'),
             },
           })
         }
diff --git a/services/web/locales/en.json b/services/web/locales/en.json
index b6cd1f4d48..62e8abbfed 100644
--- a/services/web/locales/en.json
+++ b/services/web/locales/en.json
@@ -95,6 +95,7 @@
   "add_error_assist_annual_to_your_projects": "Add Error Assist Annual <sparkle/> to your projects and get unlimited AI help to fix LaTeX errors faster.",
   "add_error_assist_to_your_projects": "Add Error Assist <sparkle/> to your projects and get unlimited AI help to fix LaTeX errors faster.",
   "add_files": "Add files",
+  "add_manager_user_not_found": "This email address is not registered in Overleaf. Please ask the person you are trying to add as a manager to create an Overleaf account if they have not already done so. When adding a manager, please use one of the email addresses that are associated with their account.",
   "add_more_collaborators": "Add more collaborators",
   "add_more_licenses_to_my_plan": "Add more licenses to my plan",
   "add_more_managers": "Add more managers",