diff --git a/services/core/java/android/os/UserManagerInternal.java b/services/core/java/android/os/UserManagerInternal.java
index 38983488654eb..502400dbd8aef 100644
--- a/services/core/java/android/os/UserManagerInternal.java
+++ b/services/core/java/android/os/UserManagerInternal.java
@@ -279,4 +279,12 @@ public abstract class UserManagerInternal {
      * Gets all {@link UserInfo UserInfos}.
      */
     public abstract @NonNull UserInfo[] getUserInfos();
+
+    /**
+     * Returns {@code true} if the system should ignore errors when preparing
+     * the storage directories for the user with ID {@code userId}. This will
+     * return {@code false} for all new users; it will only return {@code true}
+     * for users that already existed on-disk from an older version of Android.
+     */
+    public abstract boolean shouldIgnorePrepareStorageErrors(int userId);
 }
diff --git a/services/core/java/com/android/server/StorageManagerService.java b/services/core/java/com/android/server/StorageManagerService.java
index 360068dc5f918..7a4d7d4da8711 100644
--- a/services/core/java/com/android/server/StorageManagerService.java
+++ b/services/core/java/com/android/server/StorageManagerService.java
@@ -3389,11 +3389,20 @@ class StorageManagerService extends IStorageManager.Stub
                     mInstaller.tryMountDataMirror(volumeUuid);
                 }
             }
-        } catch (RemoteException | Installer.InstallerException e) {
+        } catch (Exception e) {
             Slog.wtf(TAG, e);
             // Make sure to re-throw this exception; we must not ignore failure
             // to prepare the user storage as it could indicate that encryption
             // wasn't successfully set up.
+            //
+            // Very unfortunately, these errors need to be ignored for broken
+            // users that already existed on-disk from older Android versions.
+            UserManagerInternal umInternal = LocalServices.getService(UserManagerInternal.class);
+            if (umInternal.shouldIgnorePrepareStorageErrors(userId)) {
+                Slog.wtf(TAG, "ignoring error preparing storage for existing user " + userId
+                        + "; device may be insecure!");
+                return;
+            }
             throw new RuntimeException(e);
         }
     }
diff --git a/services/core/java/com/android/server/pm/UserManagerService.java b/services/core/java/com/android/server/pm/UserManagerService.java
index f5d7d9eda1ba1..02997f5a6fa1c 100644
--- a/services/core/java/com/android/server/pm/UserManagerService.java
+++ b/services/core/java/com/android/server/pm/UserManagerService.java
@@ -198,6 +198,8 @@ public class UserManagerService extends IUserManager.Stub {
     private static final String TAG_SEED_ACCOUNT_OPTIONS = "seedAccountOptions";
     private static final String TAG_LAST_REQUEST_QUIET_MODE_ENABLED_CALL =
             "lastRequestQuietModeEnabledCall";
+    private static final String TAG_IGNORE_PREPARE_STORAGE_ERRORS =
+            "ignorePrepareStorageErrors";
     private static final String ATTR_KEY = "key";
     private static final String ATTR_VALUE_TYPE = "type";
     private static final String ATTR_MULTIPLE = "m";
@@ -298,6 +300,14 @@ public class UserManagerService extends IUserManager.Stub {
 
         private long mLastRequestQuietModeEnabledMillis;
 
+        /**
+         * {@code true} if the system should ignore errors when preparing the
+         * storage directories for this user. This is {@code false} for all new
+         * users; it will only be {@code true} for users that already existed
+         * on-disk from an older version of Android.
+         */
+        private boolean mIgnorePrepareStorageErrors;
+
         void setLastRequestQuietModeEnabledMillis(long millis) {
             mLastRequestQuietModeEnabledMillis = millis;
         }
@@ -306,6 +316,14 @@ public class UserManagerService extends IUserManager.Stub {
             return mLastRequestQuietModeEnabledMillis;
         }
 
+        boolean getIgnorePrepareStorageErrors() {
+            return mIgnorePrepareStorageErrors;
+        }
+
+        void setIgnorePrepareStorageErrors() {
+            mIgnorePrepareStorageErrors = true;
+        }
+
         void clearSeedAccountData() {
             seedAccountName = null;
             seedAccountType = null;
@@ -2955,6 +2973,10 @@ public class UserManagerService extends IUserManager.Stub {
             serializer.endTag(/* namespace */ null, TAG_LAST_REQUEST_QUIET_MODE_ENABLED_CALL);
         }
 
+        serializer.startTag(/* namespace */ null, TAG_IGNORE_PREPARE_STORAGE_ERRORS);
+        serializer.text(String.valueOf(userData.getIgnorePrepareStorageErrors()));
+        serializer.endTag(/* namespace */ null, TAG_IGNORE_PREPARE_STORAGE_ERRORS);
+
         serializer.endTag(null, TAG_USER);
 
         serializer.endDocument();
@@ -3067,6 +3089,7 @@ public class UserManagerService extends IUserManager.Stub {
         Bundle legacyLocalRestrictions = null;
         RestrictionsSet localRestrictions = null;
         Bundle globalRestrictions = null;
+        boolean ignorePrepareStorageErrors = true; // default is true for old users
 
         XmlPullParser parser = Xml.newPullParser();
         parser.setInput(is, StandardCharsets.UTF_8.name());
@@ -3158,6 +3181,11 @@ public class UserManagerService extends IUserManager.Stub {
                     if (type == XmlPullParser.TEXT) {
                         lastRequestQuietModeEnabledTimestamp = Long.parseLong(parser.getText());
                     }
+                } else if (TAG_IGNORE_PREPARE_STORAGE_ERRORS.equals(tag)) {
+                    type = parser.next();
+                    if (type == XmlPullParser.TEXT) {
+                        ignorePrepareStorageErrors = Boolean.parseBoolean(parser.getText());
+                    }
                 }
             }
         }
@@ -3185,6 +3213,9 @@ public class UserManagerService extends IUserManager.Stub {
         userData.persistSeedData = persistSeedData;
         userData.seedAccountOptions = seedAccountOptions;
         userData.setLastRequestQuietModeEnabledMillis(lastRequestQuietModeEnabledTimestamp);
+        if (ignorePrepareStorageErrors) {
+            userData.setIgnorePrepareStorageErrors();
+        }
 
         synchronized (mRestrictionsLock) {
             if (baseRestrictions != null) {
@@ -4829,6 +4860,9 @@ public class UserManagerService extends IUserManager.Stub {
                             pw.println();
                         }
                     }
+
+                    pw.println("    Ignore errors preparing storage: "
+                            + userData.getIgnorePrepareStorageErrors());
                 }
             }
             pw.println();
@@ -5254,6 +5288,14 @@ public class UserManagerService extends IUserManager.Stub {
                 return allInfos;
             }
         }
+
+        @Override
+        public boolean shouldIgnorePrepareStorageErrors(int userId) {
+            synchronized (mUsersLock) {
+                UserData userData = mUsers.get(userId);
+                return userData != null && userData.getIgnorePrepareStorageErrors();
+            }
+        }
     }
 
     /**