Hello seasidefuel,
I own a copy of QuickBooks Enterprise 2016 and have faced the same frustrations as you. I do NOT work for Intuit. The following has worked for me:
In QuickBooks on the menu bar click HELP>Internet Connection Setup>Next>Advanced Connection Setting>Security (tab)>Restricted Sites>Sites. In the "Add this website to the zone:" paste or type just this part of the url address the error message is complaining about, such as cdn.optimizely.com, as an example. Click Add>Close>OK>Done.
Logoff QuickBooks and then log back in. The script error message will no longer appear.
This can be used for all script error messages when opening QuickBooks. I have encountered several. They all seem to be connected to "User Experience Enhancement" (aka User Tracking) that are not functioning correctly. Blocking them does not affect the software....other than to block some pop-up ads Intuit may try to send.
You can answer YES or NO to get past the script error message if you are not bothered by it and do not want to take the above action. It does not affect QuickBooks one way or the other.
Another interesting tidbit is that while Intuit says upgrading to the latest version will cure the problem, if you search this community, you will find some who are using supported versions of QuickBooks are running into the same Script Error problem.
