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The InCommon Federation operates a centralized Federated Error Handling Service that SPs can use to generate simple but effective error pages for the end user. The Error Handling Service offers a simplified mechanism for obtaining the errorURL value from metadata or delegating the handling of the "missing attribute" error condition if the set of IdPs is a strict subset of InCommon members.
Note that this Error Handling Service is deployed on the same production infrastructure that hosts InCommon metadata and the InCommon Discovery Service. All of these services are available 24x7 with manual failover to a redundant hot spare in the event of an outage.
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Case 1. If both the sp_entityID and idp_entityID parameters are included in the query string, the Error Handling Service constructs a simple SP-branded error page from user interface elements in SP metadata. A link to the IdP’s Error Handling URL is included in the body of the error page and the user is encouraged to visit this page at the IdP for further instructions.
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Case 2. If both the return and idp_entityID parameters are included in the query string, the Error Handling Service will determine the Error Handling URL (errorURL) of the given IdP and then redirect the client to the return URL with the errorURL included in the query string. If the IdP has no errorURL in metadata, the client is simply redirected to the return URL without any additional information.
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