If you are using cPanel roundcube email services and when you try to modify your signature and getting error of “An error occurred while saving” without able to allow you to save the setting. You may refer to this article.
With this case, I am using email user of email@example.com, hence you may refer to the step as below to resolve the issue.
1. Log into the SSH, go to the path of /home/username/etc/domain.com where my path will be /home/mickgenie/etc/mickgenie.com/.
2. Rename or delete the file named user.rcube.db where my case will be user.rcube.db.
3. Visit your RoundCube again and the problem should be resolved.