In version 6.0.0, we added support for multiple pending SSO connections to the same IdP within the one browser session. This means we remember the state for each of these SAML sessions. Azure doesn't have this type of support and only remembers the most recent SAML session.
When the SP initiates logout, we logout the earliest SAML session. This causes the error you're seeing in Azure.
To accommodate partner providers that only remember the most recent SAML session, we'll make a change to logout the most recent SAML session instead.
This should support both scenarios.
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