chown: /usr/local: Operation not permitted - issue with brew update /usr/local is not writable - MacOS 10.13.1 high sierra

Question

I am unable to do brew update because I can’t chown /usr/local:

$ brew update
Error: /usr/local is not writable. You should change the ownership
and permissions of /usr/local back to your user account:
  sudo chown -R $(whoami) /usr/local

based on this: https://github.com/Homebrew/brew/issues/385

I tried these 2 chown command but it didnt work:

$ sudo chown -R $(whoami) $(brew --prefix)
chown: /usr/local: Operation not permitted


$ sudo chown -R $(whoami) /usr/local
chown: /usr/local: Operation not permitted

Here is my /usr/local listing:

$ cd /usr/local
$ ls -al
total 56
drwxr-xr-x 23 root wheel 736 Dec 2 15:24 .
drwxr-xr-x@ 9 root wheel 288 Oct 26 00:22 ..
-rw-r--r-- 1 megasap wheel 0 Dec 2 15:11 .com.apple.installer.keep
drwxr-xr-x 16 megasap admin 512 Jan 11 14:08 .git
drwxr-xr-x 5 megasap admin 160 Dec 2 15:24 .github
-rw-r--r-- 1 megasap admin 1112 Aug 11 2016 .gitignore
-rw-r--r-- 1 megasap admin 253 Aug 11 2016 .travis.yml
-rw-r--r-- 1 megasap admin 291 Aug 11 2016 .yardopts
-rw-r--r-- 1 megasap admin 3161 Aug 11 2016 CODEOFCONDUCT.md
drwxr-xr-x 35 megasap admin 1120 Jan 11 11:35 Cellar
-rw-r--r-- 1 megasap admin 1241 Jan 26 2016 LICENSE.txt
drwxr-xr-x 9 megasap admin 288 Dec 2 15:25 Library
-rw-r--r-- 1 megasap admin 5451 Aug 11 2016 README.md
drwxr-xr-x 262 megasap admin 8384 Jan 11 23:09 bin
drwxr-xr-x 11 megasap admin 352 Dec 2 15:25 etc
drwxr-xr-x 57 megasap staff 1824 Dec 2 15:25 include
drwxr-xr-x 102 megasap staff 3264 Dec 2 15:25 lib
drwx------ 4 megasap wheel 128 Dec 2 15:24 libexec
drwxr-xr-x 3 megasap admin 96 Dec 2 15:23 n
drwxr-xr-x 34 megasap admin 1088 Dec 2 15:25 opt
drwxr-xr-x 8 megasap admin 256 Dec 2 15:24 sbin
drwxr-xr-x 16 megasap admin 512 Dec 2 15:25 share
drwxr-xr-x 8 megasap admin 256 Dec 2 15:25 var

I'm using macOS 10.13.1 high sierra.

Answer 1

Reinstalling Homebrew worked for me

/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"