How to make root volume writeable in Big Sur?

Code Block 
Disable FileVault
Reboot into recovery mode and run:csrutil authenticated-root disable
Reboot back into MacOS
Find your root mount's device - run mount and chop off the last s, e.g. if your root is /dev/disk1s2s3, you'll mount /dev/disk1s2
Create a new directory, for example ~/mountRun sudo mount -o nobrowse -t apfs DISK_PATH MOUNT_PATH, using the values from above
Modify the files under the mounted directory
Run sudo bless --folder MOUNT_PATH/System/Library/CoreServices --bootefi --create-snapshot
Reboot your system, and the changes will take place

I'm getting following error after entering

Code Block 
 sudo mount -o nobrowse -t afps /dev/disk1s5 ~/mount  

in terminal:

Code Block 
mount_apfs: volume could not be mounted: Resource busy
mount: /Users/ishanpandey/mount failed with 75

Hi guys after doing all this my monitor works now, thanks! But how to revert the steps you've stated here? I can't reactivate FileVault again...

Disable FileVaultReboot into recovery mode and run:csrutil authenticated-root disableReboot back into MacOSFind your root mount's device - run mount and chop off the last s, e.g. if your root is /dev/disk1s2s3, you'll mount /dev/disk1s2Create a new directory, for example ~/mountRun sudo mount -o nobrowse -t apfs DISKPATH MOUNTPATH, using the values from aboveModify the files under the mounted directoryRun sudo bless --folder MOUNT_PATH/System/Library/CoreServices --bootefi --create-snapshotReboot your system, and the changes will take place

How to revert these steps so that I can activate FileVault again?

BTW: for people who still have trouble with these steps: you have to copy the order "Displays" from /System/Library to /Library , and then modify your display stuff there.
For users who use another language than english. The path to your directory is still in english even if the Finder shows you another language like in my example German. My MOUNT_PATH was /Users/juri/mount
Mind the big letters! Very important!

@jurijurka
I also want to revert the FileVault.

I tried to enable the authenticated-root in the recovery mode. Guess what? I got endless rebooting. So I give up and leave FileVault closed.

@sh00tg0a1
I have the same problem!!
After writing in the recovery terminal "csrutil authenticated-root enable" I am getting infinite endless reboots! After "csrutil authenticated-root disable" the macbook works again, but I still can't activate filevault!

I urgently need FileVault, because I have previous company data on my MacBook and we MUST use FileVault for protecting the important data.

This is really a pain in the a$$! Can someone tag an apple engineer into this thread? maybe he has an idea how we can make FileVault work again! It's really a shame that Apple forces us to do this radical step so that we can use our Monitors (I have a big one from LG) and then stabs us from behind. I'm really angry!

@eskimo we need your help!

Guys. I have bad news. DON'T follow the tutorial!!! Don't do "csrutil authenticated-root disable"!!! Never ever! Else you will also break your system like I and many others did. I hate my life. So if you fellas don't want to break your macbook (you lose your major security gates), buy a new monitor and forget about the old one. If you decide to use Apple (well, I didn't decide it since I was forced), then you decide to waste a ton of money. So if you also have monitor problem, either you buy a new monitor, or you switch your OS back to windows. I really hate Apple for doing things like these. Thanks for wasting my money.

Trust me: you really don’t want to do this in Big Sur. As explained above, in order to do this you have to break the seal on the System volume. You can’t then reseal it. Ever.
Furthermore, users are reporting that before you can do that, you have to disable FileVault, and it doesn’t appear that you can re-enable that either.
If you really want to do that, then the basic requirements are outlined above, but you’re out almost on your own in doing it, and will have lost two of your two major security protections. I wish you the very best of luck – you’ll need it!
Howard.

So I would not do "csrutil authenticated-root disable" myself, but I have part of the purchased software installed in the system partition, if on previous versions of Mac OS I could do it with minimal losses for system security, now I have been fighting for a week to make the partition writable, I I need to install what I need, on what basis does Apple not give me access to my own data that is stored on my computer? Encode the files as you want, but I must have access to any section on my disk

If you've updated to macOS Big Sur, have your DisplayVendorID-* file ready but can't copy it to  /System/Library ,try /Library folder instead:

/Macintosh HD/Library/Displays/Contents/Resources/Overrides/DisplayVendorID-*

Then restart your mac and your monitor would show the correct colours :)

This worked for me on Big Sur latest version thanks a lot.

If you've updated to macOS Big Sur, have your DisplayVendorID-* file ready but can't copy it to /System/Library ,try /Library folder instead:

/Macintosh HD/Library/Displays/Contents/Resources/Overrides/DisplayVendorID-*

Then restart your mac and your monitor would show the correct colours :)

This works guys Thanks to erfanglmpr

Can someone please explain how to copy it to /Library folder instead? Do I have to create this folder or does it already exist? Do I have to do this in recovery mode?

@alyjohn1234 I was also struggling with this, as I tried to create the folder manually and put the plist file in like I always did. Didn't seem to work. What eventually worked for me was following this: https://gist.github.com/ejdyksen/8302862 and rather using the adaugherity version of the script that they suggest to download instead. It's used to fix EDID problems on external monitors by creating a plist file in the Library Displays Overrides folder using your monitor's values. What I just did then was to edit the created plist file in a text editor, and then replace all the contents with the contents of the plist file generated by the comsysto interface, save as sudo, unplug and replug the monitor and then using RDM I was able to choose e.g. 1080p HiDPI resolution. I hope this helps.

I need to enable HiDPI.

How you find DisplayVendorID-* for your external monitor?

I tried this command:

Code Block 
ioreg -lw0 | grep IODisplayPrefsKey

but it returns nothing on Apple DTK with Big Sur.

Yep, thats very annoying. Same on M1 MBP, MBA and MM. Looks like Apple will take a bit more freedom of us. Glad we're still allowed to use the computers we paid for.

Hi after the new 11.1 Big Sur update even if I type "csrutil authenticated-root disable" the MacBook still doesn't work LOL is my MacBook now broken? ***

I am going to delete now all my data and make a reset. But then I still have the display problem. How can I solve the display problem now without deactivating SIP? @eskimo

I've built a small program which enables you to write anywhere on your Mac again in Big Sur, check the github link for a detailed description on how to use it (use at your own risk):

writeable_root on GitHub

Cheers!