if I disable the captcha plugin, it will write the following error

jmp.sh/O0BUy5r

I left the default settings.
I sent the access.
Do you need access to FTP?

I'm sorry, access from abroad was forbidden.
It's already allowed.

notice.
Since tomorrow there will be no SSL available on the test page.
Need SSL? If yes, I move domain.
Accesses have been retained.

I keep you there and approaches are working.
Page is mujtest .8u .cz/index.php? option=com_users&view=registration&Itemid=113 (remove unnecessary spaces in url)
Do you want to see the mistake yet?
This is an installation error where there is only the last joomla and the last K2 and the protostar template.

K2 registration still reports an error and does not work

Hello

I just wanted to report that the same registration error appears to Joomla! 3.7.5 Stable and makes it impossible for anyone to register.
Tried all the above suggestions and when joomla and k2 google captcha is enabled i see above the captcha box the message "Please enter the two words that appear below"
It is very easy to reproduce using captcha and k2 registration option.

Thank you.

1. If i disable captcha to Joomla core registration and k2 settings, i can register to k2 registration form.
At the same time i keep captcha plugin and "system global configuration" captcha enabled so that i get no error messages.

2. Now if i enable everything and keep joomla core captcha registration setting disabled the k2 registration form works perfect and lets me use captcha option normally. The only problem is a message above captcha box with a prompt "Please input the 2 words that appear below"

So to fix this issue i just remove the message from k2 language file
K2_ENTER_THE_TWO_WORDS_YOU_SEE_BELOW=""

Now the form works as it should :). Hope that was helpfull and clear enough.