[Home](./index.md) > [@firebase/firestore](./firestore.md) > [/](./firestore_.md) > [enableIndexedDbPersistence](./firestore_.enableindexeddbpersistence.md) ## enableIndexedDbPersistence() function Attempts to enable persistent storage, if possible. Must be called before any other functions (other than [initializeFirestore()](./firestore_.initializefirestore.md), [getFirestore()](./firestore_.getfirestore.md) or [clearIndexedDbPersistence()](./firestore_.clearindexeddbpersistence.md). If this fails, `enableIndexedDbPersistence()` will reject the promise it returns. Note that even after this failure, the `Firestore` instance will remain usable, however offline persistence will be disabled. There are several reasons why this can fail, which can be identified by the `code` on the error. \* failed-precondition: The app is already open in another browser tab. \* unimplemented: The browser is incompatible with the offline persistence implementation. Signature: ```typescript export declare function enableIndexedDbPersistence(firestore: FirebaseFirestore, persistenceSettings?: PersistenceSettings): Promise; ``` ## Parameters | Parameter | Type | Description | | --- | --- | --- | | firestore | [FirebaseFirestore](./firestore_.firebasefirestore.md) | The Firestore instance to enable persistence for. | | persistenceSettings | [PersistenceSettings](./firestore_.persistencesettings.md) | Optional settings object to configure persistence. | Returns: Promise<void> A promise that represents successfully enabling persistent storage.