A cloud-based task management app from Microsoft that helps users organize and manage daily tasks across devices.
You're right that the message doesn't fit your setup. Microsoft's own To Do doc says sharing works between personal Microsoft accounts, and that error is meant for lists owned by a work or school account. Two personal accounts that already share lists should not see it. Another couple reported the exact same error on new shares the same day, so this looks like a problem on Microsoft's side rather than with your accounts.
A few things are still worth trying, because the error is decided by which account opens the invite:
- Open the invite in a normal browser, not inside a chat or mail app. In-app browsers can be signed in to a different Microsoft account. Copy the link into Edge or Chrome in a private window.
- Sign in at to-do.live.com first with the personal account, then paste the invite link in that same window.
- Check for a second account in the To Do app. On each phone, open Settings and check whether a work or school account was ever added. If so, make sure the personal account is the one active when you open the link.
- Report it from the app so Microsoft sees it: in To Do go to Settings > Help & feedback and send a report that includes the exact error text. More reports with the same message help them track it down.
Your existing shared lists will keep syncing in the meantime. As a stopgap, you could rename one of them and reuse it for now.
Did either of you ever sign in to To Do with a work or school account on that phone?
If one of these lets you join, please consider accepting it as the answer. If the error appears even from to-do.live.com, let me know and I'll be happy to keep helping.
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