GPGMail: encryption failed: Unusable public key

David Wheeler's Avatar

David Wheeler

02 May, 2018 12:55 AM

Which of our tools is giving you problems?

The Mail extension in Mac GPG.

Attach a screenshot of the version info for all installed components (how to:


Describe your problem. Add as much detail as possible.

I am getting this popup every minute or so while I write mail. The contents of the popup are:

Unfortunately GPGMail can't handle the error at this point.

Should your problem persist, please contact us at with the following error description:

gpg: 3520844DFAA6CF90F1E9B29AD26D202CCCE1301A: skipped: Unusable public key
gpg: [stdin]: encryption failed: Unusable public key

This is the fingerprint for the key for the mail account from which I'm writing. The key is valid; I set an expiration date of April 23 2019 back on April 2018.

What did you expect instead

No dialog.

Describe steps leading to the problem.

  1. Start new message from the account with the associated key.
  2. Wait for popup/dialog.

Are you using any other plugins?

I dont think so.

  1. 1 Posted by Zlatko on 02 May, 2018 06:31 AM

    Zlatko's Avatar


    I am having same issue.

  2. Support Staff 2 Posted by Steve on 02 May, 2018 07:52 AM

    Steve's Avatar

    Hi David and Zlatko,

    welcome to the GPGTools support platform. Sorry you are having problems using GPG Suite.

    Let's check if your key is ok:

    1. open GPG Keychain
    2. double click your sec/pub key
    3. search for "Validity" in key tab and post the value to your discussion
    4. search for "Validity" in subkey tab and post the value to your discussion

    Should your key have expired, please re-new the expiration date in the key tab. To renew the subkey, click the cogwheel icon in the subkey tab and update the expiration date.

    To test the change, send a signed and encrypted test email to yourself. Are you able to decrypt and verify the signature successfully?

    In case your key resides on the public key servers, don't forget to upload your updated key, so that the changes are reflected there as well.

    We have open tickets to address this problem. Ideally GPG Keychain and GPGMail would be more pro-active about expiring keys and inform users ahead of the expiry date and explain how by extending the expiry date the key can be used in the future.

    Best regards,

  3. 3 Posted by David Wheeler on 02 May, 2018 03:07 PM

    David Wheeler's Avatar

    Oh, I have an expired subkey. I wasn't even aware that I had subkeys.

    I got a notice a few weeks ago that my keys were expiring. They had no expiration date. So I made on. I didn't even notice the subkeys tab. Will have to figure out if I even need subkeys. Also, would be nice if I could update all expiration dates for a key and its subkeys at once.

    Now off to figure out whether I need these subkeys.

  4. Support Staff 4 Posted by Steve on 02 May, 2018 03:09 PM

    Steve's Avatar

    Subkeys are expected and the default is to have one subkey.

    More info about what a Subkey is can be found here:

    The Debian Wiki has an explanation of what subkeys are as well as to why and how they are utilized. It's worth the time.

    This Stack Exchange has additional info.

  5. 5 Posted by David Wheeler on 02 May, 2018 03:12 PM

    David Wheeler's Avatar

    Ah, yes, very useful, thanks. The error is especially annoying since I almost never encrypt messages.

  6. Support Staff 6 Posted by Steve on 02 May, 2018 03:20 PM

    Steve's Avatar

    The error will be gone if you extend the subkey. We have open tickets to improve that. A warning with easy steps to fix the situation would be a good idea.

  7. 7 Posted by David Wheeler on 02 May, 2018 03:21 PM

    David Wheeler's Avatar

    Yes, fix confirmed. Thank you!

  8. Support Staff 8 Posted by Steve on 02 May, 2018 03:22 PM

    Steve's Avatar

    Perfect. Glad, this is solved for you. I'm closing this discussion. Should you need further assistance or have questions you can re-open this discussion here or open a new one any time.


  9. Steve closed this discussion on 02 May, 2018 03:22 PM.

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