1. Restarting after the install, the computer showed a gray screen and never booted up as per the original issue.
2. I booted again from the install media, opened the live session, did the workaround steps from #14 and booted into the Ubuntu 21.04 installation.
3. I enabled -proposed and ran `sudo apt install shim-signed` to upgrade that package to version 1.47+15.4-0ubuntu2.
4. I tested booting several times – cold boots, restarts and holding the option key to load the Mac boot menu – and the computer always boots normally.
5. FWIW I also then ran `sudo apt full-upgrade` to install the other available updates and the computer had continued to boot normally.
I tested on a MacBookPro9,2 (13-Inch, Mid-2012).
0. I clean installed from the 21.04 release image (http:// releases. ubuntu. com/21. 04/ubuntu- 21.04-desktop- amd64.iso). FWIW I made my usual choices
- Minimal installation
- Download updates…
- Install third-party software…
- Erase disk and install Ubuntu
1. Restarting after the install, the computer showed a gray screen and never booted up as per the original issue.
2. I booted again from the install media, opened the live session, did the workaround steps from #14 and booted into the Ubuntu 21.04 installation.
3. I enabled -proposed and ran `sudo apt install shim-signed` to upgrade that package to version 1.47+15.4-0ubuntu2.
4. I tested booting several times – cold boots, restarts and holding the option key to load the Mac boot menu – and the computer always boots normally.
5. FWIW I also then ran `sudo apt full-upgrade` to install the other available updates and the computer had continued to boot normally.