You must do some processes before Beta installation.
Uninstall the base module and the user module
At first, turn off the active value of these modules in the module management:
Then, you’ll be forward to the 2nd installer. Uninstall two modules completely. Don’t forget clicking ‘Uninstall’.
Remove the base module form your file system
You must use the legacy module instead of the base module. Therefore, you don’t need the base module. If you keep the base module, Beta may get some troubles. You must remove it. OK?
Overwrite files with the beta
Then, you will see the following screen after upgrade. Click ‘Install’ button to work the beta.