Because of recent Windows 10 updates in Office 2016, 2019 or Office 365, when you press the Add/Edit ribbon button in the JChem ribbon, with default Microsoft Office settings you will receive this error message:

The solution is the following:

1. Go fo File/Options/General menu.

2. Change the default option: "Optimize for best appearance" to "Optimize for compatibility"

3. Please note that you have to restart the application.

If you are interested in tutorials for most important features of JChem for Excel and Office, please check our Youtube Playlist: