Hi,
Today I have noticed that our installation is asking users to enter Captcha (doesn’t matter you don’t enter it) to log in. We didn’t do any upgrade, so I am wondering if there is any code in the back that pulled this now?
Cheers.
I wish our software was that intelligent 
I guess the most likely cause is a change in configuration or some installation of extension.
right, it was a plugin upgrade.
Cheers.