Client error

Hi Zoya, this message means that 2 sessions had been tried to open at the same time (possibly from different devices or different accounts). As that is not allowed anymore, the student got (or had to) logged out of one of them. Tell them to try again.

If I were you, I would start embedding from scratch which means I would delete the Login option from my site, then copy the Embedding Code and put it on the site again. Maybe the code wasn't fully copied or pasted?
(Does the Login option on your site work for you? I mean, have you tried logging in as a student? The embedding code has no errors and that option itself works correctly - I've tried it on my site and it does work!)

Ruta, thank you for explaining it.

Zoya, as Ruta explained, the system allows only one session per user. With embedding, even if the user is on "another website," the same rule applies. So when a student goes from a session on your website to the main LW website another session is started. Let me double-check if we can make this experience better for the embedding scenario. Would you mind sharing where you are embedding, or what system is it?