Online Application error message

Hello! I have a new family trying to register their kid online. They keep getting an error after they accept Terms and Conditions. It is the first time seeing this error.

Error message: “Error Code: Core API Error, Message: Not Found”

*1) Hardware: Desktop or Mobile (if mobile, please be specific)
2) Operating system
3) Browser
4) Browser cache has been cleared or you are using a private browsing mode (aka Incognito Window in Chrome)
5) Member ID & Council of person affected
Unknown- Greater Yosemite

Thank you!