Update api docs

Also change error message

app/services/users/banned_user_base_service.rb

@@ -33,7 +33,7 @@ module Users
     end
 
     def state_error(user)
-      error(_("You cannot %{action} a %{state} user." % { action: action.to_s, state: user.state }), :forbidden)
+      error(_("You cannot %{action} %{state} users." % { action: action.to_s, state: user.state }), :forbidden)
     end
 
     def allowed?

doc/api/users.md

@@ -1485,7 +1485,7 @@ Returns:
 
 - `201 OK` on success.
 - `404 User Not Found` if user cannot be found.
-- `403 Forbidden` when trying to ban a user that is blocked by LDAP synchronization or is deactivated.
+- `403 Forbidden` when trying to ban a user that is not active.
 
 ## Unban user
 
@@ -1505,7 +1505,7 @@ Returns:
 
 - `201 OK` on success.
 - `404 User Not Found` if the user cannot be found.
-- `403 Forbidden` when trying to unban a user that is blocked by LDAP synchronization or is deactivated.
+- `403 Forbidden` when trying to unban a user that is not banned.
 
 ### Get user contribution events
 

locale/gitlab.pot

@@ -38218,7 +38218,7 @@ msgstr ""
 msgid "You can view the source or %{linkStart}%{cloneIcon} clone the repository%{linkEnd}"
 msgstr ""
 
-msgid "You cannot %{action} a %{state} user."
+msgid "You cannot %{action} %{state} users."
 msgstr ""
 
 msgid "You cannot access the raw file. Please wait a minute."

spec/requests/api/users_spec.rb

@@ -2989,7 +2989,7 @@ RSpec.describe API::Users do
           ban_user
 
           expect(response).to have_gitlab_http_status(:forbidden)
-          expect(json_response['message']).to eq('You cannot ban a ldap_blocked user.')
+          expect(json_response['message']).to eq('You cannot ban ldap_blocked users.')
           expect(ldap_blocked_user.reload.state).to eq('ldap_blocked')
         end
       end
@@ -3001,7 +3001,7 @@ RSpec.describe API::Users do
           ban_user
 
           expect(response).to have_gitlab_http_status(:forbidden)
-          expect(json_response['message']).to eq('You cannot ban a deactivated user.')
+          expect(json_response['message']).to eq('You cannot ban deactivated users.')
           expect(deactivated_user.reload.state).to eq('deactivated')
         end
       end
@@ -3013,7 +3013,7 @@ RSpec.describe API::Users do
           ban_user
 
           expect(response).to have_gitlab_http_status(:forbidden)
-          expect(json_response['message']).to eq('You cannot ban a banned user.')
+          expect(json_response['message']).to eq('You cannot ban banned users.')
           expect(banned_user.reload.state).to eq('banned')
         end
       end
@@ -3070,7 +3070,7 @@ RSpec.describe API::Users do
           unban_user
 
           expect(response).to have_gitlab_http_status(:forbidden)
-          expect(json_response['message']).to eq('You cannot unban a ldap_blocked user.')
+          expect(json_response['message']).to eq('You cannot unban ldap_blocked users.')
           expect(ldap_blocked_user.reload.state).to eq('ldap_blocked')
         end
       end
@@ -3082,7 +3082,7 @@ RSpec.describe API::Users do
           unban_user
 
           expect(response).to have_gitlab_http_status(:forbidden)
-          expect(json_response['message']).to eq('You cannot unban a deactivated user.')
+          expect(json_response['message']).to eq('You cannot unban deactivated users.')
           expect(deactivated_user.reload.state).to eq('deactivated')
         end
       end
@@ -3094,7 +3094,7 @@ RSpec.describe API::Users do
           unban_user
 
           expect(response).to have_gitlab_http_status(:forbidden)
-          expect(json_response['message']).to eq('You cannot unban a active user.')
+          expect(json_response['message']).to eq('You cannot unban active users.')
           expect(user.reload.state).to eq('active')
         end
       end