Exception "Primary key property XXX has duplicate values after migration."

When I started using the migration, I began to receive periodic crash messages from crashlytics like this:

Caused by java.lang.IllegalStateException: Primary key property 'Relation.id' has duplicate values after migration.
       at io.realm.internal.OsSharedRealm.nativeGetSharedRealm(OsSharedRealm.java)
       at io.realm.internal.OsSharedRealm.<init>(OsSharedRealm.java:171)
       at io.realm.internal.OsSharedRealm.getInstance(OsSharedRealm.java:241)
       at io.realm.BaseRealm.<init>(BaseRealm.java:136)
       at io.realm.BaseRealm.<init>(BaseRealm.java:105)
       at io.realm.Realm.<init>(Realm.java:164)
       at io.realm.Realm.createInstance(Realm.java:435)
       at io.realm.RealmCache.doCreateRealmOrGetFromCache(RealmCache.java:342)
       at io.realm.RealmCache.createRealmOrGetFromCache(RealmCache.java:282)
       at io.realm.Realm.getInstance(Realm.java:364)
       at my.app.package.realm.RealmTemplate.lambda$observeObject$3(RealmTemplate.java:72)
       at my.app.package.realm.-$$Lambda$RealmTemplate$Qgzvh8wX0nrAdIuh0uNxSlktAfQ.apply(lambda)
       at io.reactivex.internal.operators.flowable.FlowableSwitchMap$SwitchMapSubscriber.onNext(FlowableSwitchMap.java:114)
       at io.reactivex.internal.operators.flowable.FlowableObserveOn$ObserveOnSubscriber.runAsync(FlowableObserveOn.java:400)
       at io.reactivex.internal.operators.flowable.FlowableObserveOn$BaseObserveOnSubscriber.run(FlowableObserveOn.java:176)
       at io.reactivex.android.schedulers.HandlerScheduler$ScheduledRunnable.run(HandlerScheduler.java:109)
       at android.os.Handler.handleCallback(Handler.java:815)
       at android.os.Handler.dispatchMessage(Handler.java:104)
       at android.os.Looper.loop(Looper.java:207)
       at android.os.HandlerThread.run(HandlerThread.java:61)

But in migration, I do not touch upon the realm object Relation. My migration:

final class Migration implements RealmMigration {
    private static final int MIN_DB_VERSION_FOR_MIGRATION = 11;
    private static final String CLASS_APP_INSTANCE = "AppInstance";

    @Override
    public void migrate(@NonNull final DynamicRealm realm, final long originalVersion, final long newVersion) {
        Timber.d("Start migration flow from DB v.%s to v.%s", originalVersion, newVersion);
        long oldVersion = originalVersion;

        if (oldVersion < MIN_DB_VERSION_FOR_MIGRATION) {
            final IllegalStateException exception = new IllegalStateException("Migration is unsupported for DB v." + originalVersion);
            Timber.w(exception);
            throw exception;
        } else {
            // Access the Realm schema in order to create, modify or delete classes and their fields.
            final RealmSchema schema = realm.getSchema();

            /*
            Migration v.11 -> v.12

            class House v.11                      ->            class House v.12
                                               add->            @Nullable String alert
            */
            if (oldVersion == MIN_DB_VERSION_FOR_MIGRATION) {
                Timber.d("Migrate DB from v.11 to v.12");
                //change schema
                schema.get("House").addField("alert", String.class);
                // Request missing data from server
                final DynamicRealmObject appInstance = realm.where(CLASS_APP_INSTANCE).findFirst();
                if (appInstance != null) {
                    appInstance.set("initialSyncDate", null);
                }
                oldVersion++;
            }

            /*
            Migration v.12 -> v.13

            class AppInstance v.12                ->            class AppInstance v.13
            String version                  rename->            String appVersion
            String versionCode              rename->            String appVersionCode
                                               add->            String osVersion
                                               add->            String osBuild
            */
            if (oldVersion == 12) {
                Timber.d("Migrate DB from v.12 to v.13");
                realm.delete(CLASS_APP_INSTANCE);
                //change schema
                schema.get(CLASS_APP_INSTANCE)
                        .renameField("version", "appVersion")
                        .renameField("versionCode", "appVersionCode")
                        .addField("osVersion", String.class)
                        .addField("osBuild", String.class);
                oldVersion++;
            }

            /*
            Migration v.13 -> v.14

            class PendingFilledField v.13         ->            class PendingFilledField v.14
            boolean deleted;                remove->

            class Address v.13                    ->            class Address v.14
            String geoLAT              change type->            Double geoLAT
            String geoLON              change type->            Double geoLON
            */
            if (oldVersion == 13) {
                Timber.d("Migrate DB from v.13 to v.14");
                //change schema
                schema.get("PendingFilledField")
                        .removeField("deleted");
                final RealmObjectSchema address = schema.get("Address");
                address.addField("geoLAT_tmp", Double.class)
                        .transform(obj -> {
                            if (RealmFieldType.STRING == obj.getFieldType("geoLAT")) {
                                final String oldGeoLAT = obj.getString("geoLAT");
                                if (oldGeoLAT != null) {
                                    obj.setDouble("geoLAT_tmp", Double.parseDouble(oldGeoLAT));
                                }
                            }
                        })
                        .removeField("geoLAT")
                        .renameField("geoLAT_tmp", "geoLAT");
                address.addField("geoLON_tmp", Double.class)
                        .transform(obj -> {
                            if (RealmFieldType.STRING == obj.getFieldType("geoLON")) {
                                final String oldGeoLON = obj.getString("geoLON");
                                if (oldGeoLON != null) {
                                    obj.setDouble("geoLON_tmp", Double.parseDouble(oldGeoLON));
                                }
                            }
                        })
                        .removeField("geoLON")
                        .renameField("geoLON_tmp", "geoLON");
                oldVersion++;
            }
        }
    }

    @Override
    public boolean equals(final Object o) {
        final boolean result;
        if (this == o) {
            result = true;
        } else {
            result = o != null && getClass() == o.getClass();
        }
        return result;
    }

    @Override
    public int hashCode() {
        return 42;
    }
}

Relation class:

public class Relation extends RealmObject {
    @PrimaryKey
    private Long id;
    private House house;
    @Nullable
    private String type;
    @Nullable
    private String status;
    @Nullable
    private String fio;
    @Nullable
    private String relationReason;
}

Version of Realm and tooling

Realm version(s): 5.1.0

Realm sync feature enabled: no

Realm configuration:

new RealmConfiguration
                .Builder()
                .name(realmName)
                .schemaVersion(Constants.DB_VERSION)
                .directory(dbDir)
                .migration(MIGRATION)
                .encryptionKey(key)
                .initialData(initTx)
                .build()

Android Studio version: 3.1.2

Which Android version and device:

• Lenovo TAB3 730X, android 6.0
• Redmi Note 4, android 7.0
• Redmi 5 Plus, android 7.1.2

[jpmcosta]

I have “solved” my issue by ensuring that ids were sane by the end of the migration. Since I never depend on the ids for ordering nor I store them directly as a property in other tables, I didn’t have any other considerations. I’m not sure if this has any side effects on the relations between objects, but my main focus was on stopping the constant crashes.

private fun fixIds(realm: DynamicRealm, className: String) {
    val classSchema = realm.schema.get(className) ?: return
    if (!classSchema.isPrimaryKey("id")) return

    classSchema.removePrimaryKey()

    var maxId = realm.where(className).max("id")?.toLong() ?: NO_ID
    var previousId: Long? = null
    val objects = realm.where(className).sort("id", Sort.ASCENDING).findAll().createSnapshot()
    for (obj in objects) {
        val id = obj.getLong("id")
        if (id == NO_ID || id == previousId) {
            obj.set("id", ++maxId)
        }
        previousId = id
    }

    classSchema.addPrimaryKey("id")
}

[deeplathia]

Just had this same issue on version 5.0.1 after a migration. The only change that was made to the schema was:

   `final RealmObjectSchema baseProfileSchema = schema.get("DeviceModel");
        
    if (baseProfileSchema != null) {
            try {
                baseProfileSchema.addField("id", String.class);
            } catch (Exception e) {
                addErrorEvent();
            }
        }`

Here are the crash logs which are not at all related to the field that I’ve added:

Caused by java.lang.IllegalStateException: Primary key property 'CartAttributes.name' has duplicate values after migration. at io.realm.internal.OsSharedRealm.nativeGetSharedRealm(OsSharedRealm.java) at io.realm.internal.OsSharedRealm.<init>(OsSharedRealm.java:171) at io.realm.internal.OsSharedRealm.getInstance(OsSharedRealm.java:241) at io.realm.BaseRealm.<init>(BaseRealm.java:134) at io.realm.BaseRealm.<init>(BaseRealm.java:103) at io.realm.Realm.<init>(Realm.java:161) at io.realm.Realm.createInstance(Realm.java:446) at io.realm.RealmCache.doCreateRealmOrGetFromCache(RealmCache.java:342) at io.realm.RealmCache.createRealmOrGetFromCache(RealmCache.java:282) at io.realm.Realm.getInstance(Realm.java:375)