Steve on 13 Aug, 2018 02:09 PM
welcome to the GPGTools support platform. Sorry you are having problems using GPG Suite.
Let's check if your key is ok:
open GPG Keychain
double click your sec/pub key
search for "Validity" in key tab and post the value to your discussion
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.