"Something went wrong when executing the Add-on" error

The "Something went wrong when executing the Add-on"  error usually appears when the mobile add-on isn't correctly installed.

You should be able to fix this error by doing as follows:

1. On your computer, click your photo in the top right corner while in Gmail
2. Click Manage your Google Account.
3. Select Security in the left navigation
4. Click Manage 3rd Party Access.
5. Select Mailtrack for Gmail Add-on > Remove Access.
6. Install the Gmail Add-on as per the steps in this FAQ.