pubkey/rxdb · error · RxError

DB6

DB6

Error message

RxDB Error-Code: DB6. Hint: Error messages are not included in RxDB core to reduce build size. To show the full error messages and to ensure that you do not make any mistakes when using RxDB, use the dev-mode plugin when you are in development mode: https://rxdb.info/dev-mode.html?console=error

What it means

DB6 is thrown when a collection already exists in the internal store but with a different schema hash than the schema you are now passing to addCollections(). RxDB stores a hash of each collection's schema; re-creating a collection with a changed schema is not allowed because existing documents would not match. You must either keep the schema identical or create a schema migration / a new collection.

Source

Thrown at src/rx-database.ts:464

                    'rx-database-add-collection'
                ),
                ensureNoStartupErrors(this)
            ]);

            await Promise.all(
                putDocsResult.error.map(async (error) => {
                    if (error.status !== 409) {
                        throw newRxError('DB12', {
                            database: this.name,
                            writeError: error
                        });
                    }
                    const docInDb: RxDocumentData<InternalStoreCollectionDocType> = ensureNotFalsy(error.documentInDb);
                    const collectionName = docInDb.data.name;
                    const schema = (schemas as any)[collectionName];
                    // collection already exists but has different schema
                    if (docInDb.data.schemaHash !== await schema.hash) {
                        throw newRxError('DB6', {
                            database: this.name,
                            collection: collectionName,
                            previousSchemaHash: docInDb.data.schemaHash,
                            schemaHash: await schema.hash,
                            previousSchema: docInDb.data.schema,
                            schema: ensureNotFalsy((jsonSchemas as any)[collectionName])
                        });
                    }
                })
            );
        } catch (err) {
            /**
             * Close any pre-created storage instances on error.
             * Some instances might have failed to create (rejected promise),
             * so we catch and ignore errors during cleanup.
             */
            await Promise.all(
                Object.values(collectionStorageInstancePromises).map(

View on GitHub (pinned to af6fb65f94)

Solutions

1. Revert the schema to match the stored one, or increment the schema version and add a migrationStrategies entry for the new version.
2. During development only, delete the persisted database (e.g. clear IndexedDB or call db.remove()) so the new schema is created fresh.
3. Use RxDB's migration plugin: addCollections with the new versioned schema plus migrationStrategies so old documents are migrated.
4. Do not mutate an existing collection's schema in place; design schema changes as version +1 with a migration.

Example fix

// before
const heroSchema = { title: 'hero', version: 0, properties: { name: { type: 'string' }, age: { type: 'number' } } };
await db.addCollections({ heroes: { schema: heroSchema } });
// after
const heroSchema = { title: 'hero', version: 1, properties: { name: { type: 'string' }, age: { type: 'number' } }, required: ['name'] };
await db.addCollections({
  heroes: {
    schema: heroSchema,
    migrationStrategies: {
      0: (oldDoc) => oldDoc
    }
  }
});

const stored = await getStoredSchemaHash(db, 'heroes');
const current = await createRxSchema(heroSchema, db.hashFunction).hash;
if (stored && stored !== current) {
  heroSchema.version += 1; // and add migrationStrategies
}

function schemasEqual(a: RxJsonSchema<any>, b: RxJsonSchema<any>): boolean {
  return JSON.stringify(normalizeSchema(a)) === JSON.stringify(normalizeSchema(b));
}

try {
  await db.addCollections(defs);
} catch (err) {
  if (isRxError(err) && err.code === 'DB6') {
    console.error('Schema changed for existing collection; bump version and add migrationStrategies', err.parameters?.collection);
  } else {
    throw err;
  }
}

When it happens

Trigger: Calling addCollections() for a collection name that already exists on disk while the RxJsonSchema has been modified (added/removed/changed fields, changed version without migration strategy), so the computed schema hash differs from the stored one.

Common situations: Editing a schema during development while the old collection data persists in IndexedDB/LocalStorage; renaming or retyping fields; bumping schema version without providing a migration strategy; sharing one database between app versions with divergent schemas.

AI-assisted analysis of pubkey/rxdb@af6fb65f94 (2026-08-31). Data as JSON: /api/errors/1ff0b2246e9514ff. Report an issue: GitHub.