.ssh/config: "Bad configuration option: UseKeychain" on Mac OS Sierra 10.12.6

I am trying to set up my ssh config on the Mac (Mac OS Sierra 10.12.6) in such a way that it stores the passphrase for my ssh key in the keychain. Previously I could do that with

ssh-add -K ~/.ssh/id_rsa

But recently this doesn't seem to work anymore. Following this article there seems to be a change in the behaviour of the ssh config in Mac OS > 10.12.2 and the recommended way to fix this issue is to add UseKeychain yes to your ssh config. So here's my .ssh/config section the Host *:

Host *
  Port 22
  ServerAliveInterval 60
  ForwardAgent yes
  IdentityFile ~/.ssh/id_rsa
  AddKeysToAgent yes
  UseKeychain yes

When trying to ssh to a foreign host, I get the following error message:

$ ssh my-host
/Users/USER/.ssh/config: line 16: Bad configuration option: usekeychain

Any ideas why this happens and how I can fix it? Thanks!

Try to specify another option, namely IgnoreUnknown like below:

Host *
  IgnoreUnknown UseKeychain
  UseKeychain yes

You can find more info about this here.

If you already have an IgnoreUnknown value, use comma separated values

Host *
  IgnoreUnknown AddKeysToAgent,UseKeychain
  AddKeysToAgent yes
  UseKeychain yes

If you have multiple Host configs that use the UseKeychain option, make sure to put

Host *
  IgnoreUnknown UseKeychain

before the first host that uses the the option, e.g. put it at the top of the file.

The accepted answer helped me but did not completely solve my problem because I had multiple options that were bad. Here is an example of what it might look like if you have this issue:

Host *
  IgnoreUnknown AddKeysToAgent,UseKeychain
  AddKeysToAgent yes
  UseKeychain yes
  IdentityFile ~/.ssh/id_rsa

Instead of ssh-add type ‘open .ssh/id_rsa’ and add it to the keychain

The UseKeychain option never appeared as bad on my config, but I have in the beginning, before any other host, the following

Host *
UseKeychain yes 

Host (...)

I just commented out the line and scp/ssh started working for me again.

It's the capital -K try lowercase -k!!

ssh-add -k ~/.ssh/id_rsa

Enter passphrase for /Users/tom/.ssh/id_rsa:
Identity added: /Users/tom/.ssh/id_rsa (/Users/tom/.ssh/id_rsa)

I had the same issue and i realized that when started to generate the key by following the instructions. The first step is this.

ssh-keygen -t rsa -b 4096 -C "your_email@example.com"

I didn't change the email address but of course I have forgotten to do that :D. So make sure to not forget that step and all will be fine.