diff --git a/www/i18n/en.json b/www/i18n/en.json
index ec432d89e..6be5a0dac 100644
--- a/www/i18n/en.json
+++ b/www/i18n/en.json
@@ -405,7 +405,8 @@
     "dont-force-kill": "Do not force kill the app",
     "background-restrictions": "On Samsung and Huwaei phones, make sure that background restrictions are turned off",
     "close": "Close",
-    "proceeding-with-token": "Proceeding with OPcode: {{token}}"
+    "proceeding-with-token": "Proceeding with OPcode: {{token}}",
+    "already-logged-in": "You are already logged in with OPcode {{token}}. If you wish to use a different OPcode, please log out first."
   },
   "config": {
     "unable-read-saved-config": "Unable to read saved config",
diff --git a/www/js/App.tsx b/www/js/App.tsx
index 328e7ab29..a311ce482 100644
--- a/www/js/App.tsx
+++ b/www/js/App.tsx
@@ -18,6 +18,9 @@ import AlertBar from './components/AlertBar';
 import Main from './Main';
 import { joinWithTokenOrUrl } from './config/dynamicConfig';
 import { addStatReading } from './plugin/clientStats';
+import useAppState from './useAppState';
+import { displayErrorMsg, logDebug } from './plugin/logger';
+import i18next from 'i18next';
 
 export const AppContext = createContext<any>({});
 const CUSTOM_LABEL_KEYS_IN_DATABASE = ['mode', 'purpose'];
@@ -34,21 +37,33 @@ const App = () => {
   const appConfig = useAppConfig();
   const permissionStatus = usePermissionStatus();
 
-  const refreshOnboardingState = () => getPendingOnboardingState().then(setOnboardingState);
+  const refreshOnboardingState = () =>
+    getPendingOnboardingState().then((state) => {
+      setOnboardingState(state);
+      return state;
+    });
+
   useEffect(() => {
     refreshOnboardingState();
   }, []);
 
-  // handleOpenURL function must be provided globally for cordova-plugin-customurlscheme
-  // https://www.npmjs.com/package/cordova-plugin-customurlscheme
-  window['handleOpenURL'] = async (url: string, joinMethod: OnboardingJoinMethod = 'external') => {
-    const configUpdated = await joinWithTokenOrUrl(url);
+  async function handleTokenOrUrl(tokenOrUrl: string, joinMethod: OnboardingJoinMethod) {
+    const onboardingState = await refreshOnboardingState();
+    logDebug(`handleTokenOrUrl: onboardingState = ${JSON.stringify(onboardingState)}`);
+    if (onboardingState.route > OnboardingRoute.WELCOME) {
+      displayErrorMsg(i18next.t('join.already-logged-in', { token: onboardingState.opcode }));
+      return;
+    }
+    const configUpdated = await joinWithTokenOrUrl(tokenOrUrl);
     addStatReading('onboard', { configUpdated, joinMethod });
     if (configUpdated) {
       refreshOnboardingState();
     }
     return configUpdated;
-  };
+  }
+  // handleOpenURL function must be provided globally for cordova-plugin-customurlscheme
+  // https://www.npmjs.com/package/cordova-plugin-customurlscheme
+  window['handleOpenURL'] = (url: string) => handleTokenOrUrl(url, 'external');
 
   useEffect(() => {
     if (!appConfig) return;
@@ -61,9 +76,24 @@ const App = () => {
     // getUserCustomLabels(CUSTOM_LABEL_KEYS_IN_DATABASE).then((res) => setCustomLabelMap(res));
   }, [appConfig]);
 
+  const appState = useAppState({});
+  if (appState != 'active') {
+    // Render nothing if the app state is not 'active'.
+    // On iOS, the UI can run if the app is launched by the OS in response to a notification,
+    // in which case the appState will be 'background'. In this case, we definitely do not want
+    // to load the UI because it is not visible.
+    // On Android, the UI can only be initiated by the user - but even so, the user can send it to
+    // the background and we don't need the UI to stay active.
+    // In the future, we may want to persist some UI states when the app is sent to the background;
+    // i.e. the user opens the app, navigates away, and back again.
+    // But currently, we're relying on a 'fresh' UI every time the app goes to 'active' state.
+    logDebug(`App: appState = ${appState}; returning null`);
+    return null;
+  }
+
   const appContextValue = {
     appConfig,
-    handleOpenURL: window['handleOpenURL'],
+    handleTokenOrUrl,
     onboardingState,
     setOnboardingState,
     refreshOnboardingState,
diff --git a/www/js/TimelineContext.ts b/www/js/TimelineContext.ts
index 63a43f1ce..fc463bbee 100644
--- a/www/js/TimelineContext.ts
+++ b/www/js/TimelineContext.ts
@@ -21,7 +21,6 @@ import { getPipelineRangeTs } from './services/commHelper';
 import { getNotDeletedCandidates, mapInputsToTimelineEntries } from './survey/inputMatcher';
 import { EnketoUserInputEntry } from './survey/enketo/enketoHelper';
 import { primarySectionForTrip } from './diary/diaryHelper';
-import useAppStateChange from './useAppStateChange';
 import { isoDateRangeToTsRange, isoDateWithOffset } from './datetimeUtil';
 import { base_modes } from 'e-mission-common';
 
@@ -55,7 +54,6 @@ type ContextProps = {
 export const useTimelineContext = (): ContextProps => {
   const { t } = useTranslation();
   const appConfig = useAppConfig();
-  useAppStateChange(() => refreshTimeline());
 
   const [labelOptions, setLabelOptions] = useState<LabelOptions | null>(null);
   // timestamp range that has been processed by the pipeline on the server
diff --git a/www/js/onboarding/WelcomePage.tsx b/www/js/onboarding/WelcomePage.tsx
index 2698df5d4..ff8214578 100644
--- a/www/js/onboarding/WelcomePage.tsx
+++ b/www/js/onboarding/WelcomePage.tsx
@@ -34,7 +34,7 @@ const WelcomePage = () => {
   const { t } = useTranslation();
   const { colors } = useTheme();
   const { width: windowWidth } = useWindowDimensions();
-  const { handleOpenURL } = useContext(AppContext);
+  const { handleTokenOrUrl } = useContext(AppContext);
   const [pasteModalVis, setPasteModalVis] = useState(false);
   const [infoPopupVis, setInfoPopupVis] = useState(false);
   const [existingToken, setExistingToken] = useState('');
@@ -52,7 +52,7 @@ const WelcomePage = () => {
           AlertManager.addMessage({ text: 'No QR code found in scan. Please try again.' });
           return;
         }
-        handleOpenURL(result.text, 'scan');
+        handleTokenOrUrl(result.text, 'scan');
       },
       (error) => {
         barcodeScannerIsOpen = false;
@@ -68,7 +68,7 @@ const WelcomePage = () => {
         if (!clipboardContent?.startsWith('nrelop_') && !clipboardContent?.includes('://')) {
           throw new Error('Clipboard content is not a valid token or URL');
         }
-        handleOpenURL(clipboardContent, 'paste');
+        handleTokenOrUrl(clipboardContent, 'paste');
       } catch (e) {
         logWarn(`Tried using clipboard content ${clipboardContent}: ${e}`);
         setPasteModalVis(true);
@@ -141,7 +141,7 @@ const WelcomePage = () => {
             <Button onPress={() => setPasteModalVis(false)}>{t('login.button-decline')}</Button>
             <Button
               onPress={() =>
-                handleOpenURL(existingToken, 'textbox').catch((e) =>
+                handleTokenOrUrl(existingToken, 'textbox').catch((e) =>
                   displayError(e, `Tried using token ${existingToken}`),
                 )
               }>
diff --git a/www/js/useAppStateChange.ts b/www/js/useAppState.ts
similarity index 52%
rename from www/js/useAppStateChange.ts
rename to www/js/useAppState.ts
index 760cbd8fa..4248045af 100644
--- a/www/js/useAppStateChange.ts
+++ b/www/js/useAppState.ts
@@ -3,26 +3,30 @@
 //the executes "onResume" function that is passed in
 //https://reactnative.dev/docs/appstate based on react's example of detecting becoming active
 
-import { useEffect, useRef } from 'react';
+import { useEffect, useState } from 'react';
 import { AppState } from 'react-native';
 import { addStatReading } from './plugin/clientStats';
 
-const useAppStateChange = (onResume) => {
-  const appState = useRef(AppState.currentState);
+type Props = {
+  onResume?: () => void;
+  onChange?: (nextAppState: string) => void;
+};
+const useAppState = ({ onResume, onChange }: Props) => {
+  const [appState, setAppState] = useState(AppState.currentState);
 
   useEffect(() => {
     const subscription = AppState.addEventListener('change', (nextAppState) => {
-      if (appState.current != 'active' && nextAppState === 'active') {
-        onResume();
+      addStatReading('app_state_change', nextAppState);
+      onChange?.(nextAppState);
+      if (nextAppState == 'active' && appState != 'active') {
+        onResume?.();
       }
-
-      appState.current = nextAppState;
-      addStatReading('app_state_change', appState.current);
+      setAppState(nextAppState);
     });
     return () => subscription.remove();
   }, []);
 
-  return {};
+  return appState;
 };
 
-export default useAppStateChange;
+export default useAppState;
diff --git a/www/js/usePermissionStatus.ts b/www/js/usePermissionStatus.ts
index 5781738fd..3af18750b 100644
--- a/www/js/usePermissionStatus.ts
+++ b/www/js/usePermissionStatus.ts
@@ -1,5 +1,5 @@
 import { useEffect, useState, useMemo } from 'react';
-import useAppStateChange from './useAppStateChange';
+import useAppState from './useAppState';
 import useAppConfig from './useAppConfig';
 import { useTranslation } from 'react-i18next';
 import { useAppTheme } from './appTheme';
@@ -358,9 +358,11 @@ const usePermissionStatus = () => {
     refreshAllChecks(checkList);
   }
 
-  useAppStateChange(() => {
-    logDebug('PERMISSION CHECK: app has resumed, should refresh');
-    refreshAllChecks(checkList);
+  useAppState({
+    onResume: () => {
+      logDebug('PERMISSION CHECK: app has resumed, should refresh');
+      refreshAllChecks(checkList);
+    },
   });
 
   //load when ready