xai-org/grok-build · error

failed to open instrumentation log {:?}: {}

Error message

failed to open instrumentation log {:?}: {}

What it means

generate_chrome_trace converts an instrumentation log file into a Chrome trace JSON. It opens the resolved input path with std::fs::File::open and wraps any OS error (not-found, permission denied, is-a-directory, etc.) in this message, which embeds the path and the io::Error text.

Source

Thrown at crates/codegen/xai-grok-telemetry/src/instrumentation.rs:403

        return Ok(path);
    }
    Ok(default_log_path())
}

#[derive(Debug, Clone, Default)]
pub struct ChromeTraceOptions {
    pub input: Option<PathBuf>,
    pub output: Option<PathBuf>,
}

pub fn generate_chrome_trace(options: ChromeTraceOptions) -> Result<PathBuf> {
    let input = resolve_input_path(options.input)?;
    let output = options
        .output
        .unwrap_or_else(|| input.with_extension("trace.json"));

    let file = std::fs::File::open(&input)
        .map_err(|err| anyhow!("failed to open instrumentation log {:?}: {}", input, err))?;
    let reader = io::BufReader::new(file);

    let mut events: Vec<Value> = Vec::new();
    let mut seen = 0usize;

    for line in reader.lines() {
        let line = match line {
            Ok(line) => line,
            Err(_) => continue,
        };
        let value: Value = match serde_json::from_str(&line) {
            Ok(value) => value,
            Err(_) => continue,
        };

        let target = value.get("target").and_then(Value::as_str);
        if target != Some(TARGET) {
            continue;

View on GitHub (pinned to bc7f02eddd)

Solutions

1. Verify the input path exists: `ls -la <resolved-path>` (the error prints the resolved path)
2. Enable/check the instrumentation log output that produces the file before tracing
3. Check file permissions or run as a user with read access
4. Pass an absolute path to avoid resolve_input_path picking a different directory

Example fix

// before
let input = resolve_input_path(options.input)?;
// after
let input = resolve_input_path(options.input)?;
if !input.exists() {
    anyhow::bail!("instrumentation log not found at {}; enable instrumentation first", input.display());
}

let input = resolve_input_path(options.input)?;
if !input.is_file() {
    eprintln!("instrumentation log missing at {}", input.display());
    return;
}

fn readable_file(p: &std::path::Path) -> bool {
    p.is_file() && std::fs::File::open(p).is_ok()
}

match generate_chrome_trace(opts) {
    Err(e) if e.to_string().contains("failed to open instrumentation log") => {
        eprintln!("log missing/unreadable: {e}; enable instrumentation and rerun");
    }
    other => other,
}

When it happens

Trigger: Calling generate_chrome_trace with options.input pointing to a path that does not exist, is a directory, or is not readable by the current user after resolve_input_path resolves it.

Common situations: Instrumentation was never enabled so the log file was never created; running the trace tool from a different working directory with a relative path; insufficient permissions; wrong file passed via --input.

Related errors

• no timing events found in {:?}
• failed to create chrome trace {:?}: {}
• failed to write chrome trace: {}
• failed to read '{}': {}
• Failed to set working directory to {:?}: {}

AI-assisted analysis of xai-org/grok-build@bc7f02eddd (2026-08-31). Data as JSON: /api/errors/a91c10a917600dd6. Report an issue: GitHub.