Bootstrap RTE error with E-mail module with templates

Since a few days I receive the following error "Could not create widget BootstrapRTE.widget.BootstrapRTE: Error: Invalid template:" when I try to edit an email template in the module "E-mail module with templates" ( In the past it worked fine and I was able to create & edit templates. As far as I can see it is a problem in the add-on "Bootstrap Wysiwyg Editor" ( Does anyone have the same problem? And how do you fix it? Modeler: 6.7.1 Browser: Chrome 53.0.2785.143 m (64-bit) on Windows 10. But had the same problem with Chrome on MacOS.
1 answers

The last update was done in May this year, but I cannot recall any issues with the template. This does seem to be a Javascript error regarding loading the widget template. If you have an SLA, please contact Support and file a ticket (as this widget has Extended Support), I'll be sure to look into it. Otherwise, you could report an issue on Github.

As Mitchel says in the comment, I'd test upgrading the widget first and see if this solves the problem.