beeradmoore/dlss-swapper · error · Exception

DownloadFileToStreamAsync returned false.

Error message

DownloadFileToStreamAsync returned false.

What it means

During DownloadAndInstallAsync the updater starts a task that downloads the new installer file into a stream (DownloadFileToStreamAsync). That helper reports success/failure as a bool; when it returns false the download did not complete, so the update cannot proceed and the code throws.

Solutions

1. Retry the download; transient network failures are the most common cause. Add automatic retry with backoff around the download task.
2. Check network connectivity and any proxy/firewall blocking github.com/objects.githubusercontent.com.
3. Verify free disk space in the temp download location.
4. Download the installer manually from the GitHub releases page and install it if automatic download keeps failing.

Example fix

// before
var didDownload = await downloaderTask;
if (didDownload == false)
    throw new Exception("DownloadFileToStreamAsync returned false.");
// after
var didDownload = await downloaderTask;
if (didDownload == false)
{
    downloadingDialog.Hide();
    throw new Exception("Update download failed. Check your network connection and try again.");
}

// Pre-check network and disk space before starting the download
if (System.Net.NetworkInformation.NetworkInterface.GetIsNetworkAvailable() == false)
    return; // don't attempt download
var drive = new DriveInfo(Path.GetTempPath());
if (drive.AvailableFreeSpace < requiredInstallerSize)
    return; // not enough space

try
{
    await updater.DownloadAndInstallAsync();
}
catch (Exception ex) when (ex.Message.Contains("DownloadFileToStreamAsync"))
{
    logger.LogWarning(ex, "Update download failed; prompt user to retry");
    // show retry dialog instead of crashing
}

When it happens

Trigger: DownloadFileToStreamAsync returns false: network interruption mid-download, GitHub returning a non-success status, the download stream failing to write, or the HTTP response being empty.

Common situations: Unstable Wi-Fi or VPN dropping mid-download, corporate proxy blocking the GitHub release download URL, insufficient disk space on the temp drive, or GitHub CDN (objects.githubusercontent.com) errors.

Related errors

• Could not download file.
• Could not find dll in zip.
• Downloaded file was invalid.
• Could not load GitHub release data.
• Could not launch installer

AI-assisted analysis of beeradmoore/dlss-swapper@ab9b1e2d4b (2026-09-15). Data as JSON: /api/errors/a7f979ce684730a6. Report an issue: GitHub.

Appendix: source

Thrown at src/Data/GitHub/GitHubUpdater.cs:365

            var fileDownloader = new FileDownloader(gitHubAsset.BrowserDownloadUrl);

            try
            {
                using (var fileStream = File.Create(tempDownloadFile))
                {
                    var downloaderTask = fileDownloader.DownloadFileToStreamAsync(fileStream, cancellationTokenSource.Token, progressCallback: (downloadedBytes, totalBytes, percent) =>
                    {
                        var displayPercent = percent * 100;
                        progressRun.Text = $"{ByteSize.FromBytes(downloadedBytes).MegaBytes.ToString("F2", CultureInfo.CurrentCulture)} / {totalSizeString} ({percent:F1}%)";
                        filesProgressBar.IsIndeterminate = false;
                        filesProgressBar.Value = percent;
                    });


                    var didDownload = await downloaderTask;
                    if (didDownload == false)
                    {
                        throw new Exception("DownloadFileToStreamAsync returned false.");
                    }

                    downloadingDialog.Hide();
                }

            }
            catch (TaskCanceledException) when (cancellationTokenSource.IsCancellationRequested)
            {
                // User cancelled.
                downloadingDialog.Hide();
                return;
            }
            catch (Exception ex)
            {
                Logger.Error(ex);
                downloadingDialog.Hide();

                var downloadErrorDialog = new EasyContentDialog(xamlRoot)

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