Why has my free version of Outlook stopped working on my mac this morning?

Outlook for Mac is available free for personal email accounts, so that message doesn’t automatically mean you need to buy Microsoft 365.

First, check whether Outlook has opened in Legacy Outlook mode. The free experience is in the newer Outlook interface; Legacy Outlook requires a licence. If you see a New Outlook switch, turn it on. Depending on your version, the option may instead be under the Help menu.

If you’re already using the newer interface, open Outlook > Settings > Accounts. If the list is empty, try adding your email account there. Reinstalling the app can leave its saved settings behind, which could explain why reinstalling didn’t change anything.

In the meantime, sign in through your email provider’s website to check your messages. Don’t delete your Outlook profile or local data folders yet, especially if you have mail saved under “On My Computer”—those messages may not exist on the server.