NickeManarin/ScreenToGif · error · Exception

Unsuccessful download of stream.

Error message

Unsuccessful download of stream.

What it means

Thrown by WebHelper.GetStream when an HTTP GET returns a non-success status code. Unlike the GitHub helper, this method does not include the status code or URL in the message — it simply reports 'Unsuccessful download of stream'. The method is a generic stream downloader used across the application.

Source

Thrown at ScreenToGif.Util/WebHelper.cs:248

                throw;

            return resp;
        }
        catch (Exception ex)
        {
            LogWriter.Log(ex, "Get response: " + url);
        }

        return null;
    }

    public static async Task<Stream> GetStream(string url, NameValueCollection headers = null)
    {
        using var client = GetHttpClient(headers);
        var response = await client.GetAsync(url);

        if (!response.IsSuccessStatusCode)
            throw new Exception("Unsuccessful download of stream.");

        return await response.Content.ReadAsStreamAsync();
    }


    private static HttpWebRequest GetWebRequest(HttpMethod method, string url, NameValueCollection headers = null, string contentType = null, long contentLength = 0)
    {
        var request = (HttpWebRequest) WebRequest.Create(url);

        if (headers != null)
            request.Headers.Add(headers);

        request.Method = method.ToString();
        request.Proxy = GetProxy();
        request.UserAgent = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.79 Safari/537.36 Edge/14.14393";
        request.ContentType = contentType;

        if (contentLength == 0)

View on GitHub (pinned to a4d0a67c21)

Solutions

  1. Include the URL and status code in the exception message for debugging.
  2. Log the response.StatusCode and response.ReasonPhrase before throwing.
  3. Verify the URL is correct and accessible from a browser or curl.
  4. Ensure required headers (User-Agent, Authorization) are passed via the headers parameter.

Example fix

// before
if (!response.IsSuccessStatusCode)
    throw new Exception("Unsuccessful download of stream.");

// after: include URL and status code
if (!response.IsSuccessStatusCode)
    throw new HttpRequestException($"Unsuccessful download of stream from '{url}': {(int)response.StatusCode} {response.ReasonPhrase}");
Defensive patterns

Strategy: try-catch

Validate before calling

// Pre-validate URL format and reachability
if (!Uri.TryCreate(url, UriKind.Absolute, out var uri))
    throw new ArgumentException($"Invalid URL: {url}");
if (uri.Scheme != Uri.UriSchemeHttp && uri.Scheme != Uri.UriSchemeHttps)
    throw new ArgumentException("Only HTTP/HTTPS URLs are supported.");

Try / catch

try
{
    return await WebHelper.GetStream(url, headers);
}
catch (Exception ex)
{
    LogWriter.Log(ex, $"Failed to download stream from {url}");
    throw new InvalidOperationException($"Download failed for '{url}': {ex.Message}", ex);
}

Prevention

When it happens

Trigger: client.GetAsync(url) returns a non-2xx response for any URL passed to GetStream. This could be a 404 (resource not found), 403 (forbidden), 500 (server error), or any other error. The URL, headers, or proxy configuration may be wrong.

Common situations: Downloaded resource URL changed or was removed. Proxy or firewall blocks the request. Server requires authentication that wasn't provided. SSL/TLS certificate issue causes a failure. The NameValueCollection headers are missing a required header (e.g., User-Agent).

Related errors

AI-assisted analysis of NickeManarin/ScreenToGif@a4d0a67c21 (2026-08-13). Data as JSON: /api/errors/2eddd139b604e8e8. Report an issue: GitHub.