http request fail: {link.Substring(0,link.IndexOf('?'))}\n{e

Error message

http request fail: {link.Substring(0,link.IndexOf('?'))}\n{e}

What it means

Thrown by HttpClientHelper.Get as a catch-all wrapping any exception during an HTTP GET. It strips the query string from the URL for the message (everything before '?') and appends the inner exception. Note: if the URL contains no '?', link.IndexOf('?') returns -1, and link.Substring(0, -1) itself throws ArgumentOutOfRangeException, masking the real error.

Source

Thrown at Packages/cn.etetet.loader/Scripts/Loader/Share/HttpClientHelper.cs:27

    {
        public static async ETTask<string> Get(string link)
        {
            try
            {
#if UNITY_WEBGL // 这里只能限制WEBGL, 因为NetClient Fiber会调用，如果改成UNITY会导致不是在主线程使用
                UnityEngine.Networking.UnityWebRequest req = UnityEngine.Networking.UnityWebRequest.Get(link);
                await req.SendWebRequest();
                return req.downloadHandler.text;
#else
                using HttpClient httpClient = new();
                HttpResponseMessage response =  await httpClient.GetAsync(link);
                string result = await response.Content.ReadAsStringAsync();
                return result;
#endif
            }
            catch (Exception e)
            {
                throw new Exception($"http request fail: {link.Substring(0,link.IndexOf('?'))}\n{e}");
            }
        }
    }
}

View on GitHub (pinned to 5cab01f7a8)

Solutions

Verify the URL is reachable from the runtime environment (correct host, port, scheme, no firewall blocking).
If the URL legitimately has no query string, note that the Substring(0, IndexOf('?')) in the catch will itself throw — patch HttpClientHelper.Get to use a safe index: link.Substring(0, link.IndexOf('?') >= 0 ? link.IndexOf('?') : link.Length).
Check server logs and network connectivity (firewall rules, DNS resolution, TLS cert validity).

Example fix

// before
throw new Exception($"http request fail: {link.Substring(0,link.IndexOf('?'))}\n{e}");
// after: guard against missing '?'
int qIdx = link.IndexOf('?');
string safeUrl = qIdx >= 0 ? link.Substring(0, qIdx) : link;
throw new Exception($"http request fail: {safeUrl}\n{e}");

Defensive patterns

Strategy: try-catch

Validate before calling

// Validate URL before calling HttpClientHelper.Get
if (string.IsNullOrWhiteSpace(link) || !Uri.TryCreate(link, UriKind.Absolute, out _))
{
    Log.Error($"Invalid URL for HttpClientHelper.Get: {link}");
    return null;
}

Try / catch

try { string result = await HttpClientHelper.Get(link); } catch (Exception e) { Log.Error($"HTTP GET failed for {link}: {e.Message}"); /* fallback or retry */ }

Prevention

Always validate URLs with Uri.TryCreate before passing to HttpClientHelper.Get.
Be aware the catch block will itself throw if the URL has no '?' character — patch HttpClientHelper.Get to guard IndexOf.
Implement retry-with-backoff for transient network failures rather than failing on first attempt.

When it happens

Trigger: Calling HttpClientHelper.Get with a URL that is unreachable, returns a non-success HTTP status, has DNS resolution failure, or has a network timeout. On WebGL builds, UnityWebRequest.SendWebRequest() failing (network error, CORS, invalid URL).

Common situations: Wrong server address or port in config. Server is down or behind a firewall. DNS not resolving in the build environment. URL missing '?' query separator causes a secondary Substring crash. SSL/TLS certificate issues on the target endpoint.

Related errors

AI-assisted analysis of egametang/ET@5cab01f7a8 (2026-08-13). Data as JSON: /api/errors/f4355244f1398e19. Report an issue: GitHub.