Trouble updating 2018 13" MBP to Catalina from Mojave

[walia6]

I'm trying to get the beta for Catalina on my MBP, but whenever I try to get the update, I get the message "An error occurred while running scripts from the package 'InstallESDDmg.pkg'. (An error occurred while installing the selected updates)"

I press OK, and hope that everything will run fine, so I run "Install macOS Catalina Beta.app"

Everyone runs smoothly, until randomly it jumps ahead to "About 15 seconds remaining", and a popup appears saying "An error occurred installing macOS. You can try again to complete the installation."

Pressing OK closes the app.

I would really appreciate some help with getting Catalina on my MBP.

What I've tried:

• running the install app again (same result)
  
  
• deleting the update and trying to re-download and install it (same result)
  
  
• restarting the machine (same result)
  
  
• ensuring date and time settings are accurate (same result)
  

Any help appreciated.