> ## Documentation Index
> Fetch the complete documentation index at: https://hedera-0c6e0218-mintlify-bc559771.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Update a file

> Update keys, contents, memo, or expiration time on a Hedera file with FileUpdateTransaction, signed by the existing and any new keys on the file.

A transaction that updates the state of an existing file on a Hedera network. Once the transaction has been processed, the network will be updated with the new field values of the file. If you need to access a previous state of the file, you can query a mirror node.

**Transaction Signing Requirements**

* The key or keys on the file are required to sign this transaction to modify the file properties
* If you are updating the keys on the file, you must sign with the old key and the new key
* If you do not sign with the key(s) on the file, you will receive an `INVALID_SIGNATURE` network error

**Transaction Fees**

* Please see the transaction and query [fees](/learn/networks/mainnet/fees#transaction-and-query-fees) table for base transaction fee
* Please use the [Hedera fee estimator](https://hedera.com/fees) to estimate your transaction fee cost

#### File Properties

| Field               | Description                                                                                                                                                                                                                                                                                                                                                                                                        |
| ------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| **Key(s)**          | Update the keys which must sign any transactions modifying this file. All keys must sign to modify the file's contents or keys. No key is required to sign for extending the expiration time (except the one for the operator account paying for the transaction). The network currently requires a file to have at least one key (or key list or threshold key) but this requirement may be lifted in the future. |
| **Contents**        | The content to update the files with.                                                                                                                                                                                                                                                                                                                                                                              |
| **Expiration Time** | If set, update the expiration time of the file. Must be in the future (may only be used to extend the expiration). To make a file inaccessible use FileDeleteTransaction.                                                                                                                                                                                                                                          |
| **Memo**            | Short publicly visible memo about the file. No guarantee of uniqueness. (100 characters max)                                                                                                                                                                                                                                                                                                                       |

| Constructor                   | Description                                  |
| ----------------------------- | -------------------------------------------- |
| `new FileUpdateTransaction()` | Initializes the FileUpdateTransaction object |

```java theme={null}
new FileUpdateTransaction()
```

### Methods

<Info>
  **Note:** The total size for a given transaction is limited to 6KiB. If you exceed this value you will need to submit a FileUpdateTransaction that is less than 6KiB and then submit a FileAppendTransaction to add the remaining content to the file.
</Info>

| Method                            | Type      | Requirement |
| --------------------------------- | --------- | ----------- |
| `setFileId(<fileId>)`             | FileId    | Required    |
| `setKey(<keys>)`                  | Key       | Optional    |
| `setContents(<bytes>)`            | byte \[ ] | Optional    |
| `setContents(<text>)`             | String    | Optional    |
| `setExpirationTime(<expiration>)` | Instant   | Optional    |
| `setFileMemo(<memo>)`             | String    | Optional    |

<CodeGroup>
  ```java Java theme={null}
  //Create the transaction
  FileUpdateTransaction transaction = new FileUpdateTransaction()
      .setFileId(fileId)
      .setKeys(newKey);

  //Modify the max transaction fee
  FileUpdateTransaction txFee = transaction.setMaxTransactionFee(new Hbar(3));

  //Freeze the transaction, sign with the original key, sign with the new key, sign with the client operator key and submit the transaction to a Hedera network
  TransactionResponse txResponse = txFee.freezeWith(client).sign(fileKey).sign(newKey).execute(client);

  //Get the receipt of the transaction
  TransactionReceipt receipt = txResponse.getReceipt(client);

  //Get the transaction consensus status
  Status transactionStatus = receipt.status;

  System.out.println("The transaction consensus status is " +transactionStatus);

  //v2.0.0
  ```

  ```javascript JavaScript theme={null}
  //Create the transaction
  const transaction = await new FileUpdateTransaction()
      .setFileId(fileId)
      .setContents("The new contents")
      .setMaxTransactionFee(new Hbar(2))
      .freezeWith(client);

  //Sign with the file private key
  const signTx = await transaction.sign(fileKey);

  //Sign with the client operator private key and submit to a Hedera network
  const submitTx = await signTx.execute(client);

  //Request the receipt
  const receipt = await submitTx.getReceipt(client);

  //Get the transaction consensus status
  const transactionStatus = receipt.status;

  console.log("The transaction consensus status " +transactionStatus3.toString());

  //v2.0.5
  ```

  ```java Go theme={null}
  //Create the transaction
  transaction := hedera.NewFileUpdateTransaction().
        SetFileID(fileId).
          SetKeys(newKey)

  //Modify the max transaction fee
  modifyMaxTransactionFee := transaction.SetMaxTransactionFee(hedera.HbarFrom(2, hedera.HbarUnits.Hbar))

  //Prepare the transaction for signing
  freezeTransaction, err := modifyMaxTransactionFee.FreezeWith(client)
  if err != nil {
          panic(err)
  }

  //Sign with the key on the file, sign with the client operator key and submit to a Hedera network
  txResponse, err := freezeTransaction.Sign(fileKey).Sign(newKey).Execute(client)
  if err != nil {
          panic(err)
  }

  //Request the receipt
  receipt, err := txResponse.GetReceipt(client)
  if err != nil {
          panic(err)
  }

  //Get the transaction status
  transactionStatus := receipt.Status

  fmt.Println("The transaction consensus status is ", transactionStatus)

  //v2.0.0
  ```

  ```rust Rust theme={null}
  // Create the transaction
  let transaction = FileUpdateTransaction::new()
      .file_id(file_id)
      .keys([new_key])
      .contents("The new contents")
      .file_memo("Updated file memo")
      .max_transaction_fee(Hbar::new(2));

  // Sign with the file key and new key
  let tx_response = transaction
      .freeze_with(&client)?
      .sign(file_key)
      .sign(new_key)
      .execute(&client).await?;

  // Request the receipt of the transaction
  let receipt = tx_response.get_receipt(&client).await?;

  // Get the transaction consensus status
  let status = receipt.status;

  println!("The transaction consensus status is {:?}", status);

  // v0.34.0
  ```
</CodeGroup>

## Get transaction values

| Method                | Type       | Requirement |
| --------------------- | ---------- | ----------- |
| `getFileId()`         | FileId     | Optional    |
| `getKey()`            | Key        | Optional    |
| `setContents()`       | ByteString | Optional    |
| `getExpirationTime()` | Instant    | Optional    |
| `getFileMemo()`       | String     | Optional    |

<CodeGroup>
  ```java Java theme={null}
  //Create the transaction
  FileUpdateTransaction transaction = new FileUpdateTransaction()
      .setFileId(fileId)
      .setKeys(newKey);

  //Get the contents of a file
  Key getKey = transaction.getKey();

  //v2.0.0
  ```

  ```java JavaScript theme={null}
  //Create the transaction
  const transaction = new FileUpdateTransaction()
      .setFileId(newFileId);

  //Get the contents of a file
  const getKey = transaction.getKey();
  ```

  ```java Go theme={null}
  //Create the transaction
  transaction := hedera.NewFileUpdateTransaction().
        SetFileID(fileId).
          SetKeys(newKey)

  //Get the contents of a file
  getKey := transaction.GetKeys()

  //v2.0.0
  ```

  ```rust Rust theme={null}
  // Create the transaction
  let transaction = FileUpdateTransaction::new()
      .file_id(file_id)
      .keys([new_key]);

  // Get the key
  let key = transaction.get_key();

  // v0.34.0
  ```
</CodeGroup>