Big Sur install removed tons of files and directories

daniel Azuelos wrote:

Thanks to your answer, I found everything displaced there:

/Volumes/My_mac_name - Data/opt

And a lot of useless old directories.

I simply finished the work with an easy ( without any help about this from the Apple documentation ):

/usr/bin/sudo -s

cd /Volumes/My_mac_name\ \-\ Data

mv opt/* /opt

rmdir opt

^D

There is not any information about this missing directory within the directory placed on the Desktop:

Relocated Items.nosync

• But some more files to check and put in the right place.

Personal conclusion of a system engineer:

migration not finished,

• insufficient documentation.

Great report daniel Azuelos and good computing !

You can submit your Apple Feedback here:  http://www.apple.com/feedback 

daniel Azuelos wrote:

I installed Big Sur on a MacBook Pro. The installation went without any error message.

A few hours later trying to use commands I built and installed ( with MacPorts, Homebrew, or myself ) I discovered that they aren't there anymore.

I used to install all this local programs inside:

/opt

I had about 500 000 binaries and libraries there.

Apparently this directory was explicitely removed during the Big Sur install without any warning.

I consider this as a very bad practice.

How to find a list of all the directories which have been secretly removed during this install?

Where is this files and directories removal documented?

I have a bootable backup, but I can't do a brutal recovery of it from / because it will completely erase

the Big Sur upgrade.

Upgraded to "Big Sur" from what macOS / OS X... you do not say(?)

What I can say —

It was macOS 10.15 Catalina where the 2 Vol read only System Volume was introduced. No big change form there except the introduction of the SSV in macOS 11.0 Big Sur.

ref: About the read-only system volume in macOS Catalina or later - Apple Support

Relocated Items Folder alias—

I might look in Finder>Go>Go To Folder> copy and paste:

/Users/Shared

daniel Azuelos wrote:

High Sierra 10.13.6.

If you see a Relocated Items folder on your Mac after upgrading macOS - Apple Support