Can't use Watchman: "Operation not permitted" - watchman

Question

Since updating Watchman recently (with Homebrew) I can no longer use it to watch projects. I get
{
"version": "2022.05.30.00",
"error": "std::__1::system_error: open: /Users/Path/To/Project: Operation not permitted"
}
I initially assumed that this must simply be file access issue I could resolve in the normal way, but giving the watchman app access to Files & Folders does not resolve the issue (even with termination of all watchman processes and restart of Terminal).
For good measure, I also manually added the watchman executable to Full Disk Access (something I've never needed to do before and am not comfortable with) but this also had no effect.
I have also terminated every relevant process I can think of, and even rebooted, twice. As far as I know the only change since Watchman worked was my running brew update watchman (which I have of course also uninstalled and reinstalled).
One concern is that for some reason I have multiple entries for watchmen in System Preferences, which weirdly results in it taking several dozen attempts to whack-a-mole all of them into a checked state for access:
How do I give Watchman the permissions needs to overcome this error?

Answer 1

Update Aug-19-2022
It looks like watchman: stable 2022.08.15.00 is working fine on my Mac M1. Upon start, you need to grant access to the local folders about to be synched.
Original
I also had the problem, like many others.
I reverted to a "working" version, e.g. 2022.05.16.00
There are multiple ways to do so; one (without private taps) would be:
Uninstall watchman
Downgrade the watchman.rb formula to an older version
https://github.com/Homebrew/homebrew-core/find/master
Navigate to watchman.rb
History -> select needed version -> View file -> Raw
Copy link to raw data
replace formula with that from raw version link
Install watchman according to that version
Pin it (to prevent further watchman updates)
Finally reset the watchman.rb formula to the original state again
# -- 1 -- uninstall
brew uninstall watchman
# -- 2 -- replace formula
curl https://raw.githubusercontent.com/Homebrew/homebrew-core/8651d8e23d308e564414188509f864e40548f514/Formula/watchman.rb > /opt/homebrew/Library/Taps/homebrew/homebrew-core/Formula/watchman.rb
# -- 3 -- install again, using replaced formula
brew install watchman
# -- 4 -- pin that version - Don't forget to unpin once this problem is solved...
brew pin watchman
# -- 5 -- reset formula to original
cd /opt/homebrew/Library/Taps/homebrew/homebrew-core/Formula/
git checkout -- watchman.rb
Then shutdown any lingering instances of Watchman with
watchman shutdown-server
Remark: On Intel-Macs, homebrews repository is located at a different place. You can find out by calling brew --repository.
Typically, the Formula is expected in directory /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core/Formula
Once the problems with watchman are solved, you can unpin watchman again and use the normal brew update/upgrade machanism.

Answer 2

On my M1 Mac:
My issue was that watchman didn't have permissions to ~/Documents folder. I don't know if this was the case before or after reinstalled it. Here are the steps I took:
brew uninstall watchman
brew install watchman
watchman shutdown-server (just in case it's running)
watchman watch-del-all
yarn start --reset-cache
When I tried to launch metro, MacOS prompted me to give permissions. After accepting, the bundler ran without issue.

Answer 3

It seems that the problem is that the watchman didn't have permission to access the ~/Documents folder. 🤔 Reinstalling watchmen seems to work as it triggers the grant access prompt.