What causes "Downloaded file is empty" in gitbutlerapp/gitbutler?

Delete the partial file and retry the download

Downloaded file is empty

Error message

Downloaded file is empty

What it means

validate_tarball checks that the macOS app tarball downloaded by the installer is non-empty before attempting gzip validation. This error means fs::metadata reported a 0-byte file at the download destination, so the install is aborted rather than proceeding with a corrupt archive.

Solutions

Delete the partial file and retry the download
Check disk space and write permissions on the destination directory
Verify the release asset on the server is non-empty; re-publish if broken
Inspect network/proxy logs for aborted transfers

Example fix

// before
let resp = client.get(url).send()?;
fs::write(path, resp.bytes()?);
// after
let resp = client.get(url).send()?;
let bytes = resp.bytes()?;
anyhow::ensure!(!bytes.is_empty(), "empty response body for {url}");
fs::write(path, &bytes)?;

Defensive patterns

Strategy: validation

Validate before calling

use std::fs;
fn is_non_empty(path: &std::path::Path) -> bool {
    fs::metadata(path).map(|m| m.len() > 0).unwrap_or(false)
}

Try / catch

match result {
    Err(e) if e.to_string().contains("Downloaded file is empty") => {
        // delete partial file and retry download
    }
    other => other?,
}

Prevention

Verify HTTP response body length before writing to disk
Check Content-Length against bytes written
Retry failed/interrupted downloads with resumable ranges
Monitor disk space on the install target

When it happens

Trigger: download_and_install_app completed the HTTP download but wrote zero bytes to disk (failed transfer, empty response body, or the file was truncated/overwritten before validation).

Common situations: CDN/proxy returning an empty 200 response, network interruption mid-download, disk-full or permissions causing a truncated write, or a release asset published empty.

Related errors

AI-assisted analysis of gitbutlerapp/gitbutler@58e5313667 (2026-09-18). Data as JSON: /api/errors/f1516fde257c2b92. Report an issue: GitHub.

Appendix: source

Thrown at crates/but-installer/src/install_macos.rs:360

    }

    let required_binaries = ["gitbutler-git-askpass", "gitbutler-tauri"];

    for binary in &required_binaries {
        let binary_path = binaries_dir.join(binary);
        if !binary_path.exists() {
            bail!("Missing required binary: {binary}");
        }
    }

    Ok(())
}

fn validate_tarball(path: &Path) -> Result<()> {
    // Check if file is not empty
    let metadata = fs::metadata(path).context("Failed to read tarball metadata")?;
    if metadata.len() == 0 {
        bail!("Downloaded file is empty");
    }

    // Check for gzip magic bytes (1f 8b)
    if !is_gzip_file(path)? {
        bail!("Downloaded file does not appear to be a valid gzip archive");
    }

    Ok(())
}

/// Check if a file has valid gzip magic bytes
fn is_gzip_file(path: &Path) -> Result<bool> {
    let mut file = File::open(path).context("Failed to open file")?;
    let mut magic_bytes = [0u8; 2];

    // If we can't read 2 bytes, it's definitely not a valid gzip file
    match file.read_exact(&mut magic_bytes) {
        Ok(_) => Ok(magic_bytes == [0x1f, 0x8b]),

View on GitHub (pinned to 58e5313667)