apache/beam · error

can't get current working directory

Error message

can't get current working directory: %w

What it means

MakeJar calls os.Getwd to remember the current working directory before chdir-ing into tmpDir to pack the JAR. This error means the process working directory could not be determined (it was deleted or is unreadable), which is saved so it can be restored later.

Solutions

1. Restart the process from an existing, accessible directory (e.g. $HOME or the project root).
2. Ensure the launch directory is not deleted while the service runs.
3. Run as a user with read+execute permission on the current directory.
4. Verify the path length is within system limits.

Example fix

// before: launching from a temp dir that gets cleaned
$ cd /tmp/session-xyz && expansion-server
// after
$ cd ~/work && expansion-server

if wd, err := os.Getwd(); err != nil {
    return fmt.Errorf("current working directory is gone: %w", err)
}

jar, err := expansionx.MakeJar(ctx, target, repo, version)
if err != nil && strings.Contains(err.Error(), "working directory") {
    os.Chdir(startDir) // restore a valid cwd before retrying
    jar, err = expansionx.MakeJar(ctx, target, repo, version)
}

When it happens

Trigger: os.Getwd fails because the process's current working directory was removed (e.g. temp dir cleaned up while the process was running) or lacks read/execute permission.

Common situations: Started the expansion service from a directory that was subsequently deleted; running inside a container whose workdir was pruned; very long paths exceeding PATH_MAX.

Understand the failure class

Background: "File not found" and ENOENT errors: why libraries can't find a file that should exist — this error's family across 50 libraries.

Related errors

• can't change to old working directory
• can't change to temp directory
• chunk write failed
• error accesing path
• error creating directory

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/3687d009f40f19b1. Report an issue: GitHub.

Appendix: source

Thrown at sdks/go/pkg/beam/core/runtime/xlangx/expansionx/download.go:304

	}

	manifest, err := os.ReadFile(tmpDir + "/META-INF/MANIFEST.MF")
	if err != nil {
		return "", fmt.Errorf("error readingf: %w", err)
	}

	// trim the empty lines present at the end of MANIFEST.MF file.
	manifestLines := strings.Split(string(manifest), "\n")
	manifestLines = manifestLines[:len(manifestLines)-2]

	classpathString := fmt.Sprintf("%sClass-Path: %s\n", strings.Join(manifestLines, "\n"), strings.Join(relClasspath, " "))
	if err = os.WriteFile(tmpDir+"/META-INF/MANIFEST.MF", []byte(classpathString), 0660); err != nil {
		return "", fmt.Errorf("error writing ta manifest file: %w", err)
	}

	path, err := os.Getwd()
	if err != nil {
		return "", fmt.Errorf("can't get current working directory: %w", err)
	}

	if err = os.Chdir(tmpDir); err != nil {
		return "", fmt.Errorf("can't change to temp directory %s for creating JAR: %w", tmpDir, err)
	}

	tmpJar := filepath.Join(cacheDir, "tmp.jar")
	if err = packJar(".", tmpJar); err != nil {
		return "", fmt.Errorf("error in packJar(): %w", err)
	}

	if err = os.Chdir(path); err != nil {
		return "", fmt.Errorf("can't change to old working directory %s: %w", path, err)
	}

	return tmpJar, nil
}

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