If you’re experiencing issues syncing Evernote with your Outlook Calendar, you might encounter errors such as “Error during authentication! [o4].”
Evernote currently supports syncing with the following types of Outlook mailboxes:
- Exchange Online
- Outlook 365, the web-based version of Outlook provided through Microsoft 365 subscriptions.
If you are using Exchange 2019 (or an on-premises Exchange server), your mailbox is not currently supported for calendar syncing with Evernote.
Updated