diff --git a/app/src/main/java/org/thoughtcrime/securesms/registration/ui/restore/RemoteRestoreActivity.kt b/app/src/main/java/org/thoughtcrime/securesms/registration/ui/restore/RemoteRestoreActivity.kt
index 5b53b17e82..4f4e5fe913 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/registration/ui/restore/RemoteRestoreActivity.kt
+++ b/app/src/main/java/org/thoughtcrime/securesms/registration/ui/restore/RemoteRestoreActivity.kt
@@ -48,11 +48,14 @@ import androidx.lifecycle.Lifecycle
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import androidx.lifecycle.lifecycleScope
 import androidx.lifecycle.repeatOnLifecycle
+import com.google.android.material.dialog.MaterialAlertDialogBuilder
 import kotlinx.collections.immutable.ImmutableList
 import kotlinx.collections.immutable.persistentListOf
+import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.filterIsInstance
 import kotlinx.coroutines.flow.firstOrNull
 import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.isActive
 import kotlinx.coroutines.launch
 import org.greenrobot.eventbus.EventBus
 import org.greenrobot.eventbus.Subscribe
@@ -62,6 +65,8 @@ import org.signal.core.ui.compose.DayNightPreviews
 import org.signal.core.ui.compose.Dialogs
 import org.signal.core.ui.compose.Previews
 import org.signal.core.ui.compose.theme.SignalTheme
+import org.signal.core.util.AppUtil
+import org.signal.core.util.ThreadUtil
 import org.signal.core.util.bytes
 import org.thoughtcrime.securesms.BaseActivity
 import org.thoughtcrime.securesms.MainActivity
@@ -81,6 +86,7 @@ import org.thoughtcrime.securesms.registration.ui.shared.RegistrationScreenTitle
 import org.thoughtcrime.securesms.registration.util.RegistrationUtil
 import org.thoughtcrime.securesms.util.DateUtils
 import org.thoughtcrime.securesms.util.PlayStoreUtil
+import org.thoughtcrime.securesms.util.TextSecurePreferences
 import org.thoughtcrime.securesms.util.viewModel
 import java.util.Locale
 import kotlin.time.Duration
@@ -150,6 +156,18 @@ class RemoteRestoreActivity : BaseActivity() {
       }
     }
 
+    lifecycleScope.launch {
+      lifecycle.repeatOnLifecycle(Lifecycle.State.RESUMED) {
+        while (isActive) {
+          if (TextSecurePreferences.isUnauthorizedReceived(this@RemoteRestoreActivity)) {
+            ThreadUtil.runOnMain { showUnregisteredDialog() }
+            break
+          }
+          delay(1000)
+        }
+      }
+    }
+
     setContent {
       val state: RemoteRestoreViewModel.ScreenState by viewModel.state.collectAsStateWithLifecycle()
       val contactSupportState: ContactSupportViewModel.ContactSupportState<ContactSupportReason> by contactSupportViewModel.state.collectAsStateWithLifecycle()
@@ -225,6 +243,15 @@ class RemoteRestoreActivity : BaseActivity() {
     viewModel.updateRestoreProgress(restoreEvent)
   }
 
+  private fun showUnregisteredDialog() {
+    MaterialAlertDialogBuilder(this)
+      .setTitle(R.string.RestoreActivity__no_longer_registered_title)
+      .setMessage(R.string.RestoreActivity__no_longer_registered_message)
+      .setCancelable(false)
+      .setPositiveButton(android.R.string.ok) { _, _ -> AppUtil.clearData(this) }
+      .show()
+  }
+
   enum class ContactSupportReason {
     NetworkError, SvrBFailure
   }
diff --git a/app/src/main/java/org/thoughtcrime/securesms/restore/RestoreActivity.kt b/app/src/main/java/org/thoughtcrime/securesms/restore/RestoreActivity.kt
index fd2ab95c8b..dfca4dcdf9 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/restore/RestoreActivity.kt
+++ b/app/src/main/java/org/thoughtcrime/securesms/restore/RestoreActivity.kt
@@ -10,9 +10,18 @@ import android.content.Intent
 import android.os.Bundle
 import androidx.activity.OnBackPressedCallback
 import androidx.activity.viewModels
+import androidx.lifecycle.Lifecycle
+import androidx.lifecycle.lifecycleScope
+import androidx.lifecycle.repeatOnLifecycle
 import androidx.navigation.NavController
 import androidx.navigation.Navigation
 import androidx.navigation.fragment.NavHostFragment
+import com.google.android.material.dialog.MaterialAlertDialogBuilder
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.isActive
+import kotlinx.coroutines.launch
+import org.signal.core.util.AppUtil
+import org.signal.core.util.ThreadUtil
 import org.signal.core.util.getParcelableExtraCompat
 import org.signal.core.util.logging.Log
 import org.thoughtcrime.securesms.BaseActivity
@@ -21,6 +30,7 @@ import org.thoughtcrime.securesms.R
 import org.thoughtcrime.securesms.RestoreDirections
 import org.thoughtcrime.securesms.registration.ui.restore.RemoteRestoreActivity
 import org.thoughtcrime.securesms.util.DynamicNoActionBarTheme
+import org.thoughtcrime.securesms.util.TextSecurePreferences
 import org.thoughtcrime.securesms.util.navigation.safeNavigate
 
 /**
@@ -80,6 +90,18 @@ class RestoreActivity : BaseActivity() {
         }
       }
     )
+
+    lifecycleScope.launch {
+      lifecycle.repeatOnLifecycle(Lifecycle.State.RESUMED) {
+        while (isActive) {
+          if (TextSecurePreferences.isUnauthorizedReceived(this@RestoreActivity)) {
+            ThreadUtil.runOnMain { showUnregisteredDialog() }
+            break
+          }
+          delay(1000)
+        }
+      }
+    }
   }
 
   override fun onResume() {
@@ -106,6 +128,15 @@ class RestoreActivity : BaseActivity() {
     finish()
   }
 
+  private fun showUnregisteredDialog() {
+    MaterialAlertDialogBuilder(this)
+      .setTitle(R.string.RestoreActivity__no_longer_registered_title)
+      .setMessage(R.string.RestoreActivity__no_longer_registered_message)
+      .setCancelable(false)
+      .setPositiveButton(android.R.string.ok) { _, _ -> AppUtil.clearData(this) }
+      .show()
+  }
+
   companion object {
 
     private val TAG = Log.tag(RestoreActivity::class)
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index bd33ac1fad..fd08a08182 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -1494,6 +1494,10 @@
     <string name="RemoteRestoreActivity__not_now">Not now</string>
     <!-- Text shown on restore screen as information on what will happen if you skip -->
     <string name="RemoteRestoreActivity__your_media_will_restore_in_the_background">Your media will restore in the background. If you choose not to restore now, you won\'t be able to restore later.</string>
+    <!-- Dialog title -->
+    <string name="RestoreActivity__no_longer_registered_title">This device is no longer registered</string>
+    <!-- Dialog message -->
+    <string name="RestoreActivity__no_longer_registered_message">This is likely because you registered your Signal account on a different device.</string>
 
     <!-- GroupMentionSettingDialog -->
     <string name="GroupMentionSettingDialog_notify_me_for_mentions">Notify me for Mentions</string>
diff --git a/core-util/src/main/java/org/signal/core/util/AppUtil.java b/core-util/src/main/java/org/signal/core/util/AppUtil.java
index 6a3cd667be..3b4afe487e 100644
--- a/core-util/src/main/java/org/signal/core/util/AppUtil.java
+++ b/core-util/src/main/java/org/signal/core/util/AppUtil.java
@@ -1,9 +1,11 @@
 package org.signal.core.util;
 
+import android.app.ActivityManager;
 import android.content.Context;
 import android.content.Intent;
 
 import androidx.annotation.NonNull;
+import androidx.core.content.ContextCompat;
 
 public final class AppUtil {
 
@@ -21,4 +23,11 @@ public final class AppUtil {
     context.startActivity(defaultIntent);
     Runtime.getRuntime().exit(0);
   }
+
+  /**
+   * Clears all app data, will cause the app to stop running.
+   */
+  public static void clearData(@NonNull Context context) {
+    ContextCompat.getSystemService(context, ActivityManager.class).clearApplicationUserData();
+  }
 }