I suffered from this same issue 2 years back and here is the workaround that just worked for me.
I was unable to boot (Ubuntu 20.04) while installing (from Live USB) like you and the screen was stuck with this error message, I waited for about 15 minutes but nothing progressed. So, I just started randomly pressing arrow keys out of frustration, and I don't know how, but booting started progressing.
Then I installed the OS and did reboot. But again, the screen stuck while booting. I forced shutdown with the power button. Searched for the issue and found out that setting nomodeset option while booting in the boot time configuration can help me rid of this issue.
Solution
Step 1: Setting nomodeset while booting after OS installation
- In the boot menu, when the cursor is on "ubuntu's kernal" (generally topmost) press "e" to edit its booting configurations.
- Find the line starting with "linux".
- Replace -> “quiet splash” with “nomodeset” or add “nomodeset” before “quiet splash”
- Press –> CTRL + X to boot
Step 2: After booting successfully, now permanently set this nomodeset in your grub config file
- Open file /etc/default/grub
- Append nomodeset to GRUB_CMDLINE_LINUX_DEFAULT that will make it as GRUB_CMDLINE_LINUX_DEFAULT="quiet splash nomodeset"
- Save and exit
Step 3: Update grub and system
- sudo update-grub
- sudo apt update
- sudo apt upgrade
Now when I did reboot the system, the error was gone.
References:
- How to set nomodeset: How do I set 'nomodeset' after I've already installed Ubuntu?
- A helpful discussion on ubuntu forum: https://ubuntuforums.org/showthread.php?t=1613132
- My own blogpost on the issue: https://misternarayan.wordpress.com/2020/05/17/fixed-error-a-connection-to-the-bus-cant-be-made-in-linux-booting/