Fatal Exception: com.google.protobuf.n1: Protocol message had invalid UTF-8

Description:
I’m encountering a recurring crash in my Android app (prod only) related to DataStore and Protocol Buffers. The crash log indicates an issue with invalid UTF-8 during the deserialization of a SettingsPrefs message.

Fatal Exception: com.google.protobuf.n1: Protocol message had invalid UTF-8.
   at com.google.protobuf.Utf8$DecodeUtil.handleTwoBytes(Utf8.java:1869)
   at com.google.protobuf.Utf8$DecodeUtil.access$700(Utf8.java:1831)
   at com.google.protobuf.Utf8$SafeProcessor.decodeUtf8(Utf8.java:978)
   at com.google.protobuf.Utf8.decodeUtf8(Utf8.java:318)
   at com.google.protobuf.CodedInputStream$StreamDecoder.readStringRequireUtf8(CodedInputStream.java:2313)
   at com.google.protobuf.CodedInputStreamReader.readStringRequireUtf8(CodedInputStreamReader.java:143)
   at com.google.protobuf.MessageSchema.readString(MessageSchema.java:4604)
   at com.google.protobuf.MessageSchema.mergeFromHelper(MessageSchema.java:3053)
   at com.google.protobuf.MessageSchema.mergeFrom(MessageSchema.java:2955)
   at com.google.protobuf.GeneratedMessageLite.parsePartialFrom(GeneratedMessageLite.java:1626)
   at com.google.protobuf.GeneratedMessageLite.parseFrom(GeneratedMessageLite.java:1762)
   at com.experiencealula.mobile.settings.persistence.serializer.SettingsPrefs.parseFrom(SettingsPrefs.java:1227)
   at com.sami.mobile.settings.data.persistence.serializer.SettingsSerializer.readFrom(SettingsSerializer.kt)
   at androidx.datastore.core.SingleProcessDataStore.readData(SingleProcessDataStore.kt:381)
   at androidx.datastore.core.SingleProcessDataStore.readDataOrHandleCorruption(SingleProcessDataStore.kt:359)
   at androidx.datastore.core.SingleProcessDataStore.readAndInit(SingleProcessDataStore.kt:322)
   at androidx.datastore.core.SingleProcessDataStore.readAndInitOrPropagateAndThrowFailure(SingleProcessDataStore.kt:302)
   at androidx.datastore.core.SingleProcessDataStore.handleUpdate(SingleProcessDataStore.kt:281)
   at androidx.datastore.core.SingleProcessDataStore.access$getFile(SingleProcessDataStore.kt)
   at androidx.datastore.core.SingleProcessDataStore.access$handleUpdate(SingleProcessDataStore.kt)
   at androidx.datastore.core.SingleProcessDataStore$actor$3.invokeSuspend(SingleProcessDataStore.kt:242)
   at androidx.datastore.core.SingleProcessDataStore$actor$3.invoke(SingleProcessDataStore.kt:1)
   at androidx.datastore.core.SingleProcessDataStore$actor$3.invoke(SingleProcessDataStore.kt:2)
   at androidx.datastore.core.SimpleActor$offer$2.invokeSuspend(SimpleActor.kt:122)
   at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
   at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:106)
   at kotlinx.coroutines.internal.LimitedDispatcher$Worker.run(LimitedDispatcher.java:115)
   at kotlinx.coroutines.scheduling.TaskImpl.run(Tasks.kt:100)
   at kotlinx.coroutines.scheduling.CoroutineScheduler.runSafely(CoroutineScheduler.java:584)
   at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.executeTask(CoroutineScheduler.kt:793)
   at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.runWorker(CoroutineScheduler.kt:697)
   at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.run(CoroutineScheduler.kt:684)

Implementation Details:
I’m using Android Jetpack Compose with Kotlin to manage settings persistence using DataStore and Protocol Buffers. Here are the relevant parts of my implementation.

SettingsPersistenceModule:

@[Module InstallIn(SingletonComponent::class)]
internal object SettingsPersistenceModule {

  private const val SETTINGS_PREFS = "settings_prefs"

  private val Context.settingsPrefs: DataStore<SettingsPrefs>
    by dataStore(
      fileName = SETTINGS_PREFS,
      serializer = SettingsSerializer,
      corruptionHandler = ReplaceFileCorruptionHandler(
        produceNewData = { SettingsPrefs.getDefaultInstance() }
      )
    )

  @[Provides Singleton]
  internal fun cache(
    @ApplicationContext context: Context
  ): DataStore<SettingsPrefs> =
    context.settingsPrefs
}

SettingsSerializer:

internal object SettingsSerializer : Serializer<SettingsPrefs> {

  override val defaultValue: SettingsPrefs = SettingsPrefs.getDefaultInstance()

  override suspend fun readFrom(input: InputStream): SettingsPrefs {
    return try {
      SettingsPrefs.parseFrom(input)
    } catch (exception: InvalidProtocolBufferException) {
      Log.e("SettingsSerializer", "Cannot read proto: ${exception.message}", exception)
      throw CorruptionException("Cannot read proto.", exception)
    }
  }

  override suspend fun writeTo(t: SettingsPrefs, output: OutputStream) {
    t.writeTo(output)
  }
}

ProtoFile:

syntax = "proto3";

option java_package = "com.sami.mobile.settings.persistence.serializer";
option java_multiple_files = true;

message SettingsPrefs {
  bool has_onboarding_seen = 1;
  string current_region_topic = 2;
  string language = 3;
  string current_language_topic = 4;
  string profile_title = 5;
  string my_bookings_title = 6;
  string my_interests_title = 7;
  string settings_title = 8;
  string help_title = 9;
  string faq_title = 10;
  string contact_title = 11;
  string preferences_title = 12;
  string language_title = 13;
  string push_notification_title = 14;
  string push_notification_description = 15;
  string policies_title = 16;
  EmergencyContactPrefs emergencyContact = 17;
  AppearanceOptionPrefs appearanceOption = 18;
  AppearancePrefs appearance = 19;
  repeated PolicyPrefs policies = 20;
  int64 review_timer = 21;
  bool show_in_app_review = 22;
  string newsletter_title = 23;
  WeatherConfigPrefs weatherConfigs = 24;
  string find_booking_title = 25;
  bool show_login = 26;
  bool clear_cart = 27;
}

message EmergencyContactPrefs {
  string description = 1;
  string information = 2;
  repeated string phoneNumbers = 3;
  string subTitlePopup = 4;
  string title = 5;
  string titlePopup = 6;
}

message AppearancePrefs {
  string title = 1;
  string lightModeTitle = 2;
  string darkModeTitle = 3;
  string deviceSettingsLabel = 4;
  string disclaimer = 5;
}

message PolicyPrefs {
  string id = 1;
  string path = 2;
  string title = 3;
}

message WeatherConfigPrefs {
  string profileId = 1;
  string locationId = 2;
  string token = 3;
}

enum AppearanceOptionPrefs {
  DEVICE_DEFAULT = 0;
  LIGHT_MODE = 1;
  DARK_MODE = 2;
}