File Sharing Problems

How to Fix Microsoft To Do Task Assignment Link Not Working

Huda Qurayshi Sep 29, 2026 869 views

Question details

The user needs to resolve an issue where a shared Microsoft To Do task assignment link is invalid, fails to open, or does not grant access to the intended recipient.

Fix Microsoft To Do Task Assignment Link Not Working

Product: Microsoft To Do
Device & OS: not provided
Scenario: Sharing a task or list with another user to collaborate on projects.
Observed behavior: The shared task assignment link does not work, preventing the recipient from accessing the list or accepting the assigned task.

Before you start

Ensure you have a stable internet connection and verify with the sender that they have not accidentally deleted the task list or manually revoked your access permissions.

Solution 1Recommended

Verify Account Permissions and Regenerate the Sharing Link

Ensure both users are signed into the correct Microsoft accounts and that the sharing link is fresh and valid.

Often, assignment links fail because the recipient is logged into a different Microsoft account than the one intended, or the original link has expired. Regenerating the link can quickly resolve this.

Check Microsoft account sign-in

Open Microsoft To Do and verify that both the sender and recipient are signed into the correct, matching Microsoft 365 accounts.

Stop sharing the current list

Have the sender open the shared list, click the 'Share' icon at the top right, select 'Manage access', and click 'Stop sharing'.

Regenerate a new link

Click the 'Share' icon again to create a brand new invitation link, and send this new link to the recipient.

Open in an incognito window

If using a web browser, the recipient should paste the new link into a private or incognito window to bypass any conflicting cached account logins.

Verify Account Permissions and Regenerate the Sharing Link

Work or School Accounts: If you are using a Microsoft 365 work or school account, your organization's IT policies might restrict external sharing. Contact your admin if internal links work but external ones do not.

Solution 2

Update the Microsoft To Do App

Install the latest app updates to resolve bugs or syncing issues that prevent links from opening properly.

Solution 3

Check Microsoft 365 Service Health

Determine if a server-side incident is temporarily breaking Microsoft To Do sharing features.

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Frequently Asked Questions

Why does my Microsoft To Do invitation link say it is invalid?

Invitation links become invalid if the original sender has clicked 'Stop sharing', generated a new link, or completely deleted the shared list. You will need to ask the list owner to generate and send a new link.

Can I share a Microsoft To Do task with someone outside my organization?

Yes, but this depends entirely on your organization's Microsoft 365 IT policies. If your network administrator has disabled external sharing, assignment links will only work for users within your company's domain.

How can I revoke access to a shared list in Microsoft To Do?

Open the shared list in the Microsoft To Do app, click on the 'Share' icon located at the top right, select 'Manage access', and finally click 'Stop sharing'. This immediately invalidates the existing link and removes access for other users.

Document & File Issues