Check the following:
- The application name in the URL for the Redirect URI (eSchoolPlus, TAC, HAC, EOAdmin, EORegistrar, EOParent) should match the virtual directory name that is configured in IIS on the client server. It is best to double check IIS to make sure the virtual directories match.
- The domain host name and the virtual directory name in the redirect URI must match exactly with the URL that users use to access the applications. This comparison is case-sensitive.