How to Fix 'gpg failed to sign the data' Error in Git Commit Signing

Jan 27, 2025 · 2 min read

How to Fix 'gpg failed to sign the data' Error in Git Commit Signing

Are you encountering the error: gpg failed to sign the data message when trying to sign your Git commits with GPG? This issue prevents successful commit signing and can disrupt your workflow. In this article, we’ll explain what causes this error and provide step-by-step solutions to fix it across different platforms.

Key Takeaways

The gpg failed to sign the data error occurs when Git cannot use GPG to sign commits.
Common causes include GPG installation issues, expired keys, and misconfigured Git settings.
Troubleshooting involves verifying GPG installation, checking key validity, and setting environment variables.
Platform-specific solutions may require updating GPG, configuring Pinentry, or modifying execution policies.
Always verify signed commits to ensure the signature is valid.

Understanding the ‘gpg failed to sign the data’ Error

The gpg failed to sign the data error occurs when Git is unable to use GPG (GNU Privacy Guard) to sign your commits. This can happen for several reasons:

GPG is not installed or configured correctly
Your GPG key has expired or is invalid
Git’s gpg.program or user.signingkey settings are misconfigured
The GPG_TTY environment variable is not set properly

Fixing this error requires diagnosing the specific cause and applying the appropriate solution.

Troubleshooting Steps

Before attempting platform-specific fixes, follow these general troubleshooting steps:

Verify GPG installation:
```
gpg --version
```
Check if GPG can sign data:
```
echo "test" | gpg --clearsign
```

List available GPG keys:

gpg --list-secret-keys --keyid-format=long

If these commands reveal issues like Inappropriate ioctl for device or Unusable secret key, proceed with the platform-specific solutions below.

Fixing ‘gpg failed to sign the data’ on macOS

Uninstall existing GPG:
```
brew uninstall gpg
```
Install GPG2 and Pinentry:
```
brew install gpg2 pinentry-mac
```

Configure Pinentry:

echo "pinentry-program $(brew --prefix)/bin/pinentry-mac" >> ~/.gnupg/gpg-agent.conf

Restart the GPG agent:
```
killall gpg-agent
```
Generate a new GPG key:
```
gpg --full-generate-key
```

Configure Git to use the new key:

git config --global user.signingkey <new-key-id>
git config --global gpg.program gpg

Enable commit signing:
```
git config --global commit.gpgsign true
```

Fixing ‘gpg failed to sign the data’ on Linux

Set the GPG_TTY environment variable:
```
export GPG_TTY=$(tty)
```
Add the following line to your shell profile (e.g., ~/.bashrc, ~/.zshrc):
```
export GPG_TTY=$(tty)
```
Configure Git to use the correct GPG program:
```
git config --global gpg.program gpg2
```

Fixing ‘gpg failed to sign the data’ on Windows

Open Git Bash or PowerShell as an administrator.
Set the execution policy to allow running scripts:
```
Set-ExecutionPolicy AllSigned
```
Generate a new GPG key:
```
gpg --full-generate-key
```

Configure Git to use the new key:

git config --global user.signingkey <new-key-id>

Enable commit signing:
```
git config --global commit.gpgsign true
```

Verifying Signed Commits

After successfully signing a commit, verify it with:

git log --show-signature -1

This command displays the commit’s GPG signature information.

FAQs

GPG is a powerful encryption tool that allows you to sign your Git commits, verifying the commit author's identity and ensuring the integrity of the commit data.

Run `gpg --list-keys` and check the expiration date next to your key. If the date has passed, your key has expired.

Yes, you can export your GPG key and import it on other systems to maintain a consistent signing identity.

Conclusion

By following the troubleshooting steps and platform-specific solutions outlined in this article, you should be able to resolve the gpg failed to sign the data error and successfully sign your Git commits with GPG. Ensure that GPG is properly installed and configured, your key is valid, and Git settings are correctly set up. Remember to always verify your signed commits to maintain the integrity of your Git repository.

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