How to understand the `gpg failed to sign the data` problem in git

README.md

Problem

You have installed GPG, then tried to commit and suddenly you see this error message after it:

error: gpg failed to sign the data
fatal: failed to write commit object

Debug

For understanding what's going on, first check what git is doing, so add GIT_TRACE=1 at the beginning of the command you used before (git commit or git rebase):

GIT_TRACE=1 git commit

With that you can see what GPG is doing: Probably you will see something like this

10:37:22.346480 run-command.c:637       trace: run_command: gpg --status-fd=2 -bsau <your GPG key>

(Check if your GPG key is correct)

Execute that gpg command again in the command line:

gpg --status-fd=2 -bsau <your GPG key>

👆🏻 With this now you could see what happened in detail!

Solutions

We can have many problems, but I list what I found:

1. It could be that the GPG key was expired: https://stackoverflow.com/a/47561300/532912

2. Another thing could be that the secret key was not set properly (In my case the message said gpg: signing failed: No secret key as it can be see in the image below). It means that is not finding the key that was set. You would need to set up the GPG key in Git (again):

   • List the secret keys available in GPG.

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

   • Copy your key
   • Set your key for your user in git

   git config --global user.signingkey <your key>

3. Another popular solution that could help was shared here by @NirajanMahara: https://gist.github.com/paolocarrasco/18ca8fe6e63490ae1be23e84a7039374?permalink_comment_id=3767413#gistcomment-3767413

4. You can see in the thread of this gist other ways to find the solution to other problems. I recommend to read the Github guide for signing commits with GPG.

Hope it helps!

I ran this issue because I had a repo holding onto an expired local key, while I was trying to use a global key. So, even though I had run git config --global user.signingkey ABCDE, it wasn't using key ABCDE. If I ran GIT_TRACE as described above, then pulled out the gpg2 --status-fd=2 -bsau FEDCBA & ran it separately, I would get

gpg: skipped "FEDCBA": No secret key

[GNUPG:] INV_SGNR 9 FEDCBA

[GNUPG:] FAILURE sign 17

Confirmed the repo was reference the expired key by running git config --get user.signingkey. Fix was to run git config --unset user.signingkey which removed the local key. Thereafter, the repo used the global key (ABCDE).

On MacOS, I have to install pinentry-mac to enter passphrase

brew install pinentry-mac
echo "pinentry-program $(which pinentry-mac)" >> ~/.gnupg/gpg-agent.conf
killall gpg-agent

This is the true solution 👍

This worked for me as well. Thanks @bdangeb6tp !!

Still works in July 2024

git config --global gpg.program 'C:\Program Files (x86)\GnuPG\bin\gpg.exe'

Thank you for your help! It worked for me!

After upgrading my OSX to Monterey it stoped to work without reason. The GIT_TRACE didn't help to much because everything was correctly set. In the end I reinstalled the GPG Sutie via brew with the command brew reinstall --cask gpg-suite and it fixed the issue.

Doing this resolved my issue. Thanks!

That helped me, thanks!

I you're on WSL2, maybe this can help:

* Add those lines to `~/.gnupg/gpg.conf`
  ```
  use-agent 
  pinentry-mode loopback
  ```

* Add this line to `~/.gnupg/gpg-agent.conf`
  ```
  allow-loopback-pinentry
  ```

OMG tysm, I literally had no idea why gpg just froze and have to wait like 5 minute to prompt the passphrase, that sometimes even broken (i typed correctly but it still said incorrect). TYSM

In my case, the error was caused because I wrote the config line as signkey instead of signingkey...

I you're on WSL2, maybe this can help:

• Add those lines to ~/.gnupg/gpg.conf

  use-agent 
  pinentry-mode loopback
  

• Add this line to ~/.gnupg/gpg-agent.conf

  allow-loopback-pinentry
  

This worked for me after trying all methods to resolve with m3 chip

below was my error when signing commits

14:40:24.528193 exec-cmd.c:139          trace: resolved executable path from Darwin stack: /Library/Developer/CommandLineTools/usr/bin/git
14:40:24.528684 exec-cmd.c:238          trace: resolved executable dir: /Library/Developer/CommandLineTools/usr/bin
14:40:24.529477 git.c:460               trace: built-in: git commit -S -m 'signed commit'
14:40:24.533313 run-command.c:655       trace: run_command: gpg --status-fd=2 -bsau <gpgKey>
error: gpg failed to sign the data
fatal: failed to write commit object

On MacOS, I have to install pinentry-mac to enter passphrase

brew install pinentry-mac
echo "pinentry-program $(which pinentry-mac)" >> ~/.gnupg/gpg-agent.conf
killall gpg-agent

Thanks for this!

10th-Jan-2024; Still works (mac m1)

And still working in September 2024, cheers!

On MacOS, I have to install pinentry-mac to enter passphrase

brew install pinentry-mac
echo "pinentry-program $(which pinentry-mac)" >> ~/.gnupg/gpg-agent.conf
killall gpg-agent

Thanks for this!
10th-Jan-2024; Still works (mac m1)

And still working in September 2024, cheers!

also works for me

git config --unset user.signingkey

Worked for me. Thanks!

On MacOS, I have to install pinentry-mac to enter passphrase

brew install pinentry-mac
echo "pinentry-program $(which pinentry-mac)" >> ~/.gnupg/gpg-agent.conf
killall gpg-agent

thankks for this!

On MacOS, I have to install pinentry-mac to enter passphrase

brew install pinentry-mac
echo "pinentry-program $(which pinentry-mac)" >> ~/.gnupg/gpg-agent.conf
killall gpg-agent

Well over a year later and this solved the problem for me!