Fix PHPStorm ssh client error "Algorithm negotiation fail"

fixPHPStormSSH.sh

KEXALGORITHM='KexAlgorithms curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha1,diffie-hellman-group1-sha1'
ISSET_KEXALGORITHM=`grep -c "$KEXALGORITHM" /etc/ssh/sshd_config`
if [ "$ISSET_KEXALGORITHM" -eq 0 ]; then
    echo "$KEXALGORITHM" >> /etc/ssh/sshd_config
    sudo service ssh restart
fi

Works great!

Thanks for the patch. I'm still a newb, where do I add this code to fix PHPStorm?

Where is that PHPStormSSH.sh file?

You're adding this to the server you're trying to connect to

Yes, that helps connecting, but has the side effect that your server is vulnerable due to an insecure protocol... it was disabled in newer distributions of Linux by default for a reason.
I'd propose to instead update your (client side) JDK to 1.8 and even older PhpStorms work again with newer Linux servers.

For restarting the ssh service on OSX
sudo launchctl stop com.openssh.sshd
sudo launchctl start com.openssh.sshd