I'm running 6.1.3 and when I tried to recover a password for a user yesterday I was stuck due to the source code dependency on dead Captcha APIs. Instead of a captcha, there's simply an image that says:
"reCAPTCHA V1 is shutdown - direct site owners to http://g.co/recaptcha/upgrade"
Easy repro - just click on "forgot password" from the login page.
Hoping that's an easy and quick fix for 6.1.4!
Darren