When you forgot to take a backup and keep failing macOS upgrade from Mojave to Monterey

I was in the situation. Asked Apple support and he said there is no choice other than clean install. But I needed to get some files from the disk volume. At that time, what I tried but didn’t work were as follows

• NVRAM reset
• Apple Diagnostics
• First Aid
• command-R
• command-option-R
• shift-command-option-R

I came up with an idea and it worked. I’ll write down the steps

• Invoke Disk Utility on Recovery Assistant
• Add a new Volume. Let’s call it “New Volume”
• Reinstall Monterey on Recovery Assistant
• Select the new Volume “New Volume” to install Monterey
• Pray the install finishes successfully
• Migrate necessary data and settings from the old volume to the new volume
• Remove the old volume after all migrations are finished