gitbutlerapp/gitbutler · error

Effective URL is missing

Error message

Effective URL is missing

What it means

download_to_string() fetches a URL (typically a signature file) with curl and relies on curl's effective_url() to learn the final URL after redirects, for security validation. The error fires when curl followed the request but reports no effective URL (None), which should not normally happen after a successful transfer.

Solutions

  1. Retry the download; this is typically transient transport behavior
  2. Check the curl/libcurl version for known effective_url bugs and upgrade
  3. Verify network/proxy configuration isn't mangling responses
Defensive patterns

Strategy: retry

Validate before calling

// pre-check reachability and that the URL is https
let url_ok = url.starts_with("https://");

Try / catch

match download_to_string(&sig_url) {
    Ok(s) => s,
    Err(e) if e.to_string().contains("Effective URL is missing") => {
        // transient curl anomaly: retry once with backoff
        retry_with_backoff(|| download_to_string(&sig_url), 2)?
    }
    Err(e) => return Err(e),
}

Prevention

When it happens

Trigger: Calling download_and_install_app (which downloads the CLI signature via download_to_string) when the curl easy handle returns Ok(None) for effective_url — e.g. the transfer completed without a recorded final URL due to a curl/transport anomaly.

Common situations: Unusual curl versions or proxies that terminate the connection in a way that skips the effective-URL bookkeeping; pathological server responses.

Understand the failure class

Background: 'Something went wrong' / 'Request failed (500)' / 'HTTP error! status: 404' — what failed HTTP requests actually mean and how to find the real cause — this error's family across 28 libraries.

Related errors

AI-assisted analysis of gitbutlerapp/gitbutler@58e5313667 (2026-09-18). Data as JSON: /api/errors/6e4de1df77fa5a23. Report an issue: GitHub.

Appendix: source

Thrown at crates/but-installer/src/download.rs:43

            })
            .context("Failed to set write function")?;

        transfer
            .perform()
            .with_context(|| format!("Failed to download from {url}"))?;
    }

    let response_code = easy
        .response_code()
        .context("Failed to get response code")?;
    if response_code != 200 {
        bail!("Download of {url} failed with HTTP status: {response_code}");
    }

    let effective_url = easy
        .effective_url()
        .context("Failed to get effective URL")?
        .ok_or_else(|| anyhow!("Effective URL is missing"))?;

    crate::release::validate_download_url(effective_url)
        .with_context(|| format!("Download was redirected to an untrusted URL: {effective_url}"))?;

    String::from_utf8(buf.into_inner()).context("Signature file is not valid UTF-8")
}

pub(crate) fn download_file(url: &str, dest: &Path) -> Result<()> {
    let mut easy = create_client()?;

    easy.url(url)
        .with_context(|| format!("Failed to set URL: {url}"))?;

    // Enable libcurl's built-in progress reporting
    easy.progress(true)?;

    let file = File::create(dest).context("Failed to create download file")?;
    let file = std::cell::RefCell::new(file);

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