dyld: Library not loaded: /usr/local/opt/icu4c/lib/libicui18n.62.dylib error running php after installing node with brew on Mac

Update - As stated in some of the comments, running brew cleanup could possibly fix this error, if that alone doesn't fix it, you might try upgrading individual packages or all your brew packages.

I just had this same problem. Upgrading Homebrew and then cleaning up worked for me. This error likely showed up for me because of a mismatch in package versions. None of the above solutions resolved my error, but running the following homebrew commands did.

Caution - This will upgrade all your brew packages, including, but not limited to PHP. If you only want to upgrade specific packages make sure to be specific.

brew upgrade // for upgrading all packages -- this is the command I used

brew upgrade {package} // for upgrading a specific package

and finally

brew cleanup

In my case, that happened because icu4c was upgraded to version 63 but my locally installed postgres image still referenced icu4c 62.1. Therefore i had to change the icu4c version used:

 brew info icu4c
 brew switch icu4c <version>

Where version is the the installed version returned by info

I am actually quite surprised that this solution has not been presented yet, and I feel like it is the easiest solution.

Go to GitHub, find the version of the brewfile that matches the version of icu4c that you need and get the raw version of the file (follow the links above and click View File then Raw).

Then just have brew reinstall from that url.

For example, version 62.1:

brew reinstall https://raw.githubusercontent.com/Homebrew/homebrew-core/575eb4bbef683551e19f329f60456b13a558132f/Formula/icu4c.rb

For example, version 64.2:

brew reinstall https://raw.githubusercontent.com/Homebrew/homebrew-core/a806a621ed3722fb580a58000fb274a2f2d86a6d/Formula/icu4c.rb