apache/beam · error

error opening source file

Error message

error opening source file %s: %w

What it means

For each non-directory zip entry, extractJar opens the embedded file with file.Open(); this error wraps that failure along with the entry name. It means the archive entry itself could not be read — usually a corrupt or truncated zip central/local header rather than a filesystem problem, since the entry lives inside the already-opened archive.

Solutions

1. Re-download the jar and retry extraction.
2. Test the archive with `unzip -t` to confirm corruption.
3. Verify the download completed (HTTP 200 and full io.Copy) before extracting.
4. If unsupported compression, re-zip the contents with standard DEFLATE.

Example fix

// before
jarPath, err := expansionx.MakeJar(ctx, url, dest) // extract fails on truncated jar
// after
if fi, statErr := os.Stat(jarPath); statErr != nil || fi.Size() != expectedSize {
    os.Remove(jarPath)
    jarPath, err = expansionx.MakeJar(ctx, url, dest)
}

// Verify archive integrity before extraction
r, err := zip.OpenReader(jarPath)
if err != nil { return err }
for _, f := range r.File {
    rc, err := f.Open()
    if err != nil { return fmt.Errorf("entry %q unreadable; jar corrupt", f.Name) }
    rc.Close()
}

err := expansionx.MakeJar(ctx, url, dest)
if err != nil && strings.Contains(err.Error(), "error opening source file") {
    os.Remove(jarPath)
    return fmt.Errorf("corrupt jar; re-download from %s", url)
}

When it happens

Trigger: file.Open() (zip.File.Open) fails during extractJar: corrupt entry metadata, unsupported compression method, or truncated archive bytes.

Common situations: Partially downloaded jar (connection cut mid-copy); jar damaged in transit through a mangling proxy; archive using a compression method Go's archive/zip doesn't support.

Understand the failure class

Background: "open() failed", "failed to open file", "cannot create file" — what a file open error means and how to fix it — this error's family across 42 libraries.

Related errors

• error copying file
• error creating jarFile header
• error opening jar for extractJar
• bucket must not be empty
• chunk write failed

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/1ab8556806e4ca91. Report an issue: GitHub.

Appendix: source

Thrown at sdks/go/pkg/beam/core/runtime/xlangx/expansionx/download.go:176

	}

	if err := os.MkdirAll(dest, 0700); err != nil {
		return fmt.Errorf("error creating directory %s in extractJar(%s,%s): %w", dest, source, dest, err)
	}

	for _, file := range reader.File {
		fileName, err := validatePath(dest, file.Name)
		if err != nil {
			return fmt.Errorf("error validating file path (%s, %s): %w", dest, file.Name, err)
		}
		if file.FileInfo().IsDir() {
			os.MkdirAll(fileName, 0700)
			continue
		}

		sf, err := file.Open()
		if err != nil {
			return fmt.Errorf("error opening source file %s: %w", file.Name, err)
		}
		defer sf.Close()

		df, err := os.OpenFile(fileName, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0777)
		if err != nil {
			return fmt.Errorf("error opening destination file %s: %w", fileName, err)
		}
		defer df.Close()

		if _, err := io.Copy(df, sf); err != nil {
			return err
		}
	}
	return nil
}

func packJar(source, dest string) error {
	jar, err := os.Create(dest)

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