What is the common cause when a customer sees the error regarding a "Required String parameter 'RelayState' is not present"?

The error message indicating that a "Required String parameter 'RelayState' is not present" typically arises in the context of Single Sign-On (SSO) implementations. In IdP-initiated SSO flows, the Identity Provider (IdP) sends the user directly to a service provider without the necessary parameters that the service provider expects, such as 'RelayState'.

In IdP-initiated SSO, the IdP does not communicate with the service provider prior to the authentication process, which means it does not include all the required parameters. The 'RelayState' parameter is used to preserve the state of the user's session or redirect URL within the SSO flow, and its absence can lead to this specific error. Therefore, when a customer encounters this error, it suggests that the process they are following does not adequately include (or requires) this parameter due to the nature of the IdP-initiated flow.

Other options, while relevant in different contexts, do not directly address the absence of the 'RelayState' parameter. For instance, a user being assigned to a client application or issues related to metadata and expired SSL certificates might cause other types of errors in an SSO implementation, but they wouldn’t specifically result in this particular