If your Chromebook displays an error message when accessing a specific webpage (such as: ‘Aw, Snap!’ or ‘This webpage is unavailable’):
Check your internet connection (the Wi-Fi icon in the bottom right corner shows you are connected to the Wi-Fi).
Close all other tabs, apps and extensions.
Try to access the webpage again.
If it still doesn’t work, remove your account and try again. There is a chance that the website you are trying to access is blocked by the district's firewalls.