Upgrading to macOS Sierra (v10.12) notes and observations

Here I'll compile some notes on my upgrade from ElCapitan to macOS Sierra (v10.12).

I'll update this post as I find new things. Please comment if you also find things.

Passwordless ssh authentication not working anymore

macOS Sierra brings in a newer version of openssh that deprecate DSA key by default. So if your using DSA keys your passwordless ssh will fait and you will be prompted for a password.

If you invoke your ssh in verbose mode you will see something like:

    debug1: Skipping ssh-dss key /Users/courchea/.ssh/id_dsa - not in PubkeyAcceptedKeyTypes

The fix is quite easy. Simply add the following in ~/.ssh/config:

    Host *        PubkeyAcceptedKeyTypes +ssh-dss

But for better security you should consider ditching DSA keys.

Brew upgrade complaining about missing xcrun

If you try to do a brew upgrade, you may get the following error:

xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun

READ THIS: https://git.io/brew-troubleshooting
If reporting this issue please do so at (not Homebrew/brew):
  https://github.com/Homebrew/homebrew-core/issues

To fix this you need to re-run the xcode command line tools install:

xcode-select --install