105a106,118
> diff --git a/src/Destination/DrupalDirectoryDestination.php b/src/Destination/DrupalDirectoryDestination.php
> index f95566e..506948e 100644
> --- a/src/Destination/DrupalDirectoryDestination.php
> +++ b/src/Destination/DrupalDirectoryDestination.php
> @@ -53,7 +53,7 @@ class DrupalDirectoryDestination extends DirectoryDestination {
>            ['%dir' => $dir]
>          );
>        }
> -      if (!file_prepare_directory($dir, FILE_CREATE_DIRECTORY && FILE_MODIFY_PERMISSIONS)) {
> +      if (!\Drupal::service('file_system')->prepareDirectory($dir, FILE_CREATE_DIRECTORY && FILE_MODIFY_PERMISSIONS)) {
>          throw new BackupMigrateException(
>            "The backup file could not be saved to '%dir' because the directory could not be created or cannot be written to. Please make sure your private files directory is writable by the web server.",
>            ['%dir' => $dir]
259a273,311
> diff --git a/tests/src/Functional/BackupMigratePageLoadTest.php b/tests/src/Functional/BackupMigratePageLoadTest.php
> index 9fd9bb6..3a8f2aa 100644
> --- a/tests/src/Functional/BackupMigratePageLoadTest.php
> +++ b/tests/src/Functional/BackupMigratePageLoadTest.php
> @@ -32,7 +32,7 @@ class BackupMigratePageLoadTest extends BrowserTestBase {
>      // `admin/config/development/backup_migrate/backups` path will fail without
>      // this.
>      $path = 'private://backup_migrate/';
> -    file_prepare_directory($path, FILE_CREATE_DIRECTORY);
> +    \Drupal::service('file_system')->prepareDirectory($path, FILE_CREATE_DIRECTORY);
>    }
>  
>    /**
> diff --git a/tests/src/Functional/BackupMigratePermissionsTest.php b/tests/src/Functional/BackupMigratePermissionsTest.php
> index c13ec52..fdd7d93 100644
> --- a/tests/src/Functional/BackupMigratePermissionsTest.php
> +++ b/tests/src/Functional/BackupMigratePermissionsTest.php
> @@ -48,7 +48,7 @@ class BackupMigratePermissionsTest extends BrowserTestBase {
>  
>      // Ensure the backup_migrate folder exists.
>      $path = 'private://backup_migrate/';
> -    file_prepare_directory($path, FILE_CREATE_DIRECTORY);
> +    \Drupal::service('file_system')->prepareDirectory($path, FILE_CREATE_DIRECTORY);
>    }
>  
>    /**
> diff --git a/tests/src/Functional/BackupMigrateQuickBackupTest.php b/tests/src/Functional/BackupMigrateQuickBackupTest.php
> index 4bb4515..78fc484 100644
> --- a/tests/src/Functional/BackupMigrateQuickBackupTest.php
> +++ b/tests/src/Functional/BackupMigrateQuickBackupTest.php
> @@ -29,7 +29,7 @@ class BackupMigrateQuickBackupTest extends BrowserTestBase {
>  
>      // Ensure backup_migrate folder exists.
>      $path = 'private://backup_migrate/';
> -    file_prepare_directory($path, FILE_CREATE_DIRECTORY);
> +    \Drupal::service('file_system')->prepareDirectory($path, FILE_CREATE_DIRECTORY);
>    }
>  
>    /**