Login via sso from another domain

Support SSO
1

If a user from the a.a.com domain goes to the b.b.com discourse site, an error occurs
How can it be solved?
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If a user from domain a.a.com goes to the discourse site b.a.com, the login is successful
Why does this happen?
I need a transition from a.a.com to b.b.com. How to realize this?

In /logs: Verbose SSO log: Nonce is incorrect, was generated in a different browser session, or has expired

2

I was able to find a solution if anyone is interested.
The problem was with cookies, they were blocked during crossdomain request.
Solution to the problem:
In the discourse settings set the “same site cookies” field to None.
This setting allows you to access cookies to a site with a different domain.
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