You updated an AD Connect with IIS installation to AD Connect and SSO is broken.
See this Ping Knowledge Base article for instructions to correct the issue.
AD Connect installer did not download.
If for some reason the AD Connect installer is not automatically downloaded to the AD Connect host during an auto-update, you will need to manually install the new version of AD Connect.
Rolling back to a previous version.
If necessary, you can roll back to a previous version of AD Connect. Just uninstall the existing AD Connect version and install the desired version. If you decide you want to upgrade at some point, you will need to authorize the auto-update.