This is the answer SkaDate support:

This error is indicating that somebody accidentally left a vardump code. 
If third party developer was doing any work on your site, please contact him and ask to remove it for you. 

Quote from alcalacr

This is the answer SkaDate support:

This error is indicating that somebody accidentally left a vardump code. 
If third party developer was doing any work on your site, please contact him and ask to remove it for you. 

Quote from alcalacr we believe that the error started after installing the plugin.
I was not sure if it was failure SkaDate plugin or failure.

I am interested in your plugin much. we think it's a great idea.
how we can fix the error?

Quote from alcalacr I've uninstalled the plugin that was purchased and installed.
Apparently the error no longer appears.

Except for the test user that was created with the webcam profile picture

I am interested in your plugin much. we think it's a great idea.
how we can fix the error?

We have solved the problem. Apparently it was not error plugin.

Thanks for all