If you click Help->Contact Support and enter the error message, you will learn the following. Basically, MS knows it's broken and a fix is coming in Q4.
Late last year we released support for sending emails and meetings to OneNote in Insiders Fast. This feature was very well received and since then, the OneNote team along with the Outlook team has iterated on feedback and have come to a conclusion that a newer version is needed in order to better support this feature across all versions of Outlook. In its place, the OneNote team will release a new version of this functionality based on the Office add-in infrastructure. This new version is currently in the last stages of testing and is scheduled to roll out to everyone in Q4 2018.
Due to the new version being rolled out, the existing version will no longer be supported and will be removed in the near future. Thank you for your patience.