Try this way:
It is necessary to set in the component options (in the "Slogin Service Autentification" section) - for the "Service auth" item - NO
(thus, it will not be authorization through the slogin.info service, which has become overloaded, but through the applications you create on each social network)
And then create and configure an authorization code (application) for each social network
(it is described how to do this - in the description for Slogin - "FaceBook - setting up social authorization", "VK - VK authorization setup using oAuth protocol", etc.).
Then the error disappears (in my site) and registration starts working normally (as before).
This way, of course, is much more difficult than using registration via the slogin.info service (= put Yes in "Service auth" - and no need to write hemorrhoid code for applications),
But it works! ))
