I’m encountering an issue with downloading SQLite database files using the FTPConnect library in Flutter. Specifically, when I attempt to download larger SQLite files (e.g., 4MB or 15MB), the downloaded files are incomplete and cannot be opened. However, smaller files of the same type download and open without any issues.

Here’s a summary of the problem:

• Library Used: FTPConnect in Flutter for FTP operations.
• Issue: Larger SQLite files are incompletely downloaded as bytes, making them unreadable.
• Observations: Smaller SQLite files download and open correctly, indicating that the issue is specific to larger file sizes.
• Attempts: I’ve tried setting the transfer type to binary (ftpConnect.setTransferType(TransferType.binary)) and handling download retries (ftpConnect.downloadFileWithRetry). Despite these efforts, larger files still download incompletely.

What could be causing this issue with FTPConnect where larger SQLite files are incompletely downloaded as bytes? How can I ensure that larger SQLite files are downloaded completely and correctly?

Code Snipped:

// Relevant code snippet used for downloading SQLite files
// Example of downloading a file with FTPConnect

Future<void> _deleteAndDownloadFile(context) async {
  showDialog(
      context: context,
      builder: (context) => const Center(child: CircularProgressIndicator()));

  var settingsProvider = Provider.of<SettingsProvider>(context, listen: false);
  var databaseProvider = Provider.of<DatabaseProvider>(context, listen: false);

  final FTPConnect ftpConnect = FTPConnect(settingsProvider.settings.ftpUrl,
      user: settingsProvider.settings.ftpUsername,
      pass: settingsProvider.settings.ftpPassword);

  try {
    // Connect to FTP server and set transfer type
    await ftpConnect.connect();
    await ftpConnect.setTransferType(TransferType.binary);
    await ftpConnect.sendCustomCommand('TYPE I');

    // Directory setup and file handling
    Directory appDocDirectory = await getApplicationDocumentsDirectory();
    Directory directory = Directory('${appDocDirectory.path}/files');

    if (!(await directory.exists())) {
      await directory.create(recursive: true);
    }

    // Delete existing file if present
    final File file = File('${directory.path}/${settingsProvider.getSavedSahaElemanNo()}.db');
    if (await file.exists()) {
      await file.delete();
    }

    // Attempt to download the SQLite file
    await ftpConnect.downloadFileWithRetry(
      '/DbFieldTeam/${settingsProvider.getSavedSahaElemanNo()}.db', file,
      pRetryCount: 2,
      onProgress: (progressInPercent, totalReceived, fileSize) =>
          print('Progress: $progressInPercent, Total Received: $totalReceived, File Size: $fileSize'));

    final int fileSize = await file.length();
    print('File size: $fileSize bytes');

    // Further database operations and error handling
    // (Open database, fetch data, update UI, etc.)

  } catch (e) {
    // Error handling for various exceptions
    print(e);
    switch (e.runtimeType) {
      case FTPConnectException:
        // Handle FTP connection issues
        break;
      case DatabaseException:
        // Handle SQLite database errors
        break;
      case SocketException:
        // Handle network connectivity issues
        break;
      default:
        // Handle other errors
        break;
    }
  } finally {
    // Close dialogs, cleanup, and navigation
    Navigator.pop(context);
  }
}