CoplayDev/unity-mcp · error · InvalidOperationException

File download failed: {(int)response.StatusCode} {response.R

Error message

File download failed: {(int)response.StatusCode} {response.ReasonPhrase} ({url})\n{body}

What it means

DownloadBytes throws when fetching a raw file from raw.githubusercontent.com returns a non-success status. This happens during ApplyPlan, after the tree listed the file, so a failure here usually indicates the file became unreachable between the tree fetch and the download.

Source

Thrown at MCPForUnity/Editor/Setup/SkillSyncService.cs:309

        internal static string DownloadString(HttpClient client, string url)
        {
            using var response = client.GetAsync(url).GetAwaiter().GetResult();
            var body = response.Content.ReadAsStringAsync().GetAwaiter().GetResult();
            if (!response.IsSuccessStatusCode)
            {
                throw new InvalidOperationException($"GitHub request failed: {(int)response.StatusCode} {response.ReasonPhrase} ({url})\n{body}");
            }

            return body;
        }

        private static byte[] DownloadBytes(HttpClient client, string url)
        {
            using var response = client.GetAsync(url).GetAwaiter().GetResult();
            if (!response.IsSuccessStatusCode)
            {
                var body = response.Content.ReadAsStringAsync().GetAwaiter().GetResult();
                throw new InvalidOperationException($"File download failed: {(int)response.StatusCode} {response.ReasonPhrase} ({url})\n{body}");
            }

            return response.Content.ReadAsByteArrayAsync().GetAwaiter().GetResult();
        }

        internal static string NormalizeRemotePath(string path)
        {
            if (string.IsNullOrWhiteSpace(path))
            {
                return string.Empty;
            }

            return path.Replace('\\', '/').Trim().Trim('/');
        }

        private static string CombineRemotePath(string left, string right)
        {
            var normalizedLeft = NormalizeRemotePath(left);

View on GitHub (pinned to c21bf496bc)

Solutions

Retry the sync (transient races and CDN blips often clear).
Confirm the file still exists at the synced commit SHA.
Check the URL in the message for path-encoding issues.
Avoid syncing while the target branch is being force-pushed.

Defensive patterns

Strategy: retry

Try / catch

try
{
    var bytes = DownloadBytes(client, url);
}
catch (InvalidOperationException ex) when (ex.Message.Contains("File download failed"))
{
    log?.Invoke($"Transient raw-file download failure for {url}. Retrying sync may help.");
    throw;
}

Prevention

Avoid syncing while the target branch is being force-pushed.
Retry once on transient raw.githubusercontent.com failures.
Check the URL for path-encoding issues when failures persist.

When it happens

Trigger: 404 because the file was deleted/renamed between the tree fetch and download (branch moved); path encoding mismatch in the constructed raw URL; transient network error or CDN issue.

Common situations: Branch advanced during a sync; special characters in the file path were not encoded as GitHub expects; intermittent raw.githubusercontent.com outage.

Related errors

AI-assisted analysis of CoplayDev/unity-mcp@c21bf496bc (2026-08-13). Data as JSON: /api/errors/19c71f9150d58554. Report an issue: GitHub.