The below doc was made with help of one of our contributors John Blaustein who was facing issue with his form using ReCaptcha 2.0.
Below is what his diagnosis was and looks like it should help other users as well facing the similar issues.
This will also help us in further researching on this issue and completely eliminate it.
"For those of you having problems using reCAPTCHA 2.0, my web hosting service solved the problem for me. I had a contact form that was working perfectly until I added the reCAPTCHA 2.0 field. When clicking Submit, I got an error: "The server encountered an error." It is now fixed and working perfectly."
Here is what their tech support person said:
"I've figured out what was causing the error. The PHP option for ‘url_fopen’ was not getting set correctly. It was set to ‘Off’, when it needed to be ‘On’ in order for the form to be submitted successfully. To set it to ‘On’, I added a custom php.ini to your account in the public_html folder (just a copy of the server's php.ini file) and change the variable for ‘url_fopen’ to ‘On’."
The php.ini file is on the server side, not the user side. I did not create or edit the php.ini file--Muse didn't either. My web hosting tech support person edited the file on the server to correct the setting which allowed the captcha to work.
My advice would be to contact your web hosting service and tell them exactly what my tech said, quote in my initial message above. Let's hope that works for you.
This document was generated from the following discussion: reCAPTCHA 2.0 server error -- SOLVED