QuickBooks Script Error arises due to an account used is already been busy in some other operations. It can be fixed by following the method over here:

• Add QuickBooks to the list of trusted sites in the settings of Internet Explorer.

• Also, stop the error notification for the script error by going to the setting and navigating to the advanced tab.

• In case the said error arises while you are browsing, then you need to delete the cache and cookies of your browser. 

• In the Internet browser, go to the tools tab to disable the add-on function in internet explorer.

Follow the step carefully, and this will help you get rid of errors.