When signing in to ArcGIS Online from ArcMap using Google credentials, the following errors are encountered:
“An error has occurred in the script on this page"and
"Google couldn't sign you in”.
This is logged as BUG-000127774.
Note: This issue also affects ArcGIS Pro, and a workaround for that product is found in the article "Bug: Unable to sign in to ArcGIS Online from ArcGIS Pro using Google credentials"
The issue occurs because a script on the Google sign-in web page is incompatible with the Internet Explorer version used for the embedded browser dialog in ArcMap.
Adjust the Internet Explorer version of the web browser using a registry key.
Warning: The instructions below include making changes to essential parts of your operating system. It is recommended that you backup your operating system and files, including the registry, before proceeding. Consult a qualified computer systems professional, if necessary. Esri cannot guarantee results from incorrect modifications while following these instructions. Therefore, use caution and proceed at your own risk.
Note: Delete your browsing history in Internet Options to clear Google credentials used with ArcMap.