What causes "Trace upload failed for session {}" in xai-org/grok-build?

Follow the printed Retry hint: `grok trace ` once connectivity/auth is restored

Trace upload failed for session {}

Error message

Trace upload failed for session {}

What it means

`TraceUpload::handle_failure` is the terminal error path of `grok trace upload`: after all retries are exhausted it exports a debug bundle, prints local bundle/log paths, and returns "Trace upload failed for session {id}". It means the session trace could not be uploaded to GCS, though a local export was produced for manual retry.

Source

Thrown at crates/codegen/xai-grok-pager/src/trace_cmd.rs:583

        if self.json {
            let result = TraceResult {
                session_id: self.session_id.to_owned(),
                status: "failed",
                url: None,
                local_path: Some(export_path.display().to_string()),
                error: Some(format!("{error}")),
            };
            println!("{}", serde_json::to_string(&result).unwrap_or_default());
        } else {
            eprintln!();
            eprintln!("Trace upload failed: {error}");
            eprintln!("  Bundle: {}", export_path.display());
            eprintln!("  Log:    {}", log_path.display());
            eprintln!("  Retry:  grok trace {}", self.session_id);
            println!("{}", export_path.display());
        }

        anyhow::anyhow!("Trace upload failed for session {}", self.session_id)
    }

    fn write_debug_log(&self, error: &anyhow::Error, output_dir: &Path) -> PathBuf {
        use std::fmt::Write;

        let log_path = output_dir.join(format!("{}.upload.log", self.session_id));
        let mut log = String::new();
        let _ = writeln!(log, "Trace upload debug log");
        let _ = writeln!(log, "======================");
        let _ = writeln!(log, "Timestamp:    {}", chrono::Utc::now().to_rfc3339());
        let _ = writeln!(log, "Grok version: {}", xai_grok_version::full_version());
        let _ = writeln!(
            log,
            "OS:           {} {}",
            std::env::consts::OS,
            std::env::consts::ARCH
        );
        let _ = writeln!(log, "Session ID:   {}", self.session_id);

View on GitHub (pinned to bc7f02eddd)

Solutions

Follow the printed Retry hint: `grok trace <session-id>` once connectivity/auth is restored
Check the written `{session}.upload.log` in the output dir for the root-cause error
Verify GCS credentials (`gcloud auth login` / GOOGLE_APPLICATION_CREDENTIALS) and bucket permissions
Inspect the exported bundle at the printed Bundle path and attach it manually if upload is permanently blocked

Example fix

// after seeing the failure, use printed artifacts
# Log:    /out/<session>.upload.log
# Retry:  grok trace <session-id>
grok trace <session-id>

Defensive patterns

Strategy: fallback

Validate before calling

// pre-flight: check network + credentials before upload
let reachable = std::net::TcpStream::connect("storage.googleapis.com:443").is_ok();
let creds = std::env::var("GOOGLE_APPLICATION_CREDENTIALS").is_ok();
if !reachable || !creds { eprintln!("upload will fail: network={} creds={}", reachable, creds); }

Try / catch

match run_upload(session).await {
    Err(e) if e.to_string().starts_with("Trace upload failed") => {
        // local bundle was exported; retry later or ship bundle manually
        eprintln!("{e}; see printed Bundle/Log paths, retry with `grok trace <session-id>`");
    }
    other => other?,
}

Prevention

Keep the exported bundle path from the failure output — it enables manual recovery
Ensure GCS credentials and bucket permissions are valid before long trace sessions
Retry uploads on stable network; the command already retries with backoff internally

When it happens

Trigger: `run_upload` -> upload attempt(s) fail (network down, GCS auth rejected, bucket permissions, timeouts on every retry), control flows to `handle_failure`, which always returns this anyhow error after writing the export bundle and `{session}.upload.log`.

Common situations: No network / VPN required for GCS; expired or missing service credentials (gcloud auth); bucket write permission revoked; proxy blocking uploads; outage at the storage backend.

Related errors

AI-assisted analysis of xai-org/grok-build@bc7f02eddd (2026-08-31). Data as JSON: /api/errors/2293aef236eaff9d. Report an issue: GitHub.