Steps to reproduce:
Setup Magento Cloud with a new 2.3 installation
Follow the steps to install the Sample Data here: https://devdocs.magento.com/guides/v2.3/cloud/howtos/sample-data.html
Upon visiting the site, an error will occur. I've tried this twice with the same result each time. Can anyone else confirm they are having this problem?
What type of error are you getting?