To Do changes for on-premises mailbox users

[Jeremy Bradshaw]

Since I don't see this having been announced in the To Do blog or in the Microsoft 365 Message Center, I'm sharing this here.

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https://support.microsoft.com/en-gb/office/changes-to-microsoft-to-do-access-for-on-premises-mailbox... 

Changes to Microsoft To Do access for on-premises mailbox accounts

Starting January 22nd, 2021, anyone who uses To Do or the Tasks app in Teams with an on-premises mailbox will only be able to sign in to To Do on the web. You won’t be able to sign in to To Do on Android, iOS, Mac, or Windows. In To Do on the web, you’ll be able to view your lists and tasks, but anything you edit or add won’t be saved and will be lost once you sign out.

Starting February 22nd, 2021, anyone with an on-premises mailbox won’t be able to sign in to To Do on any platform. Make sure to back up your To Do data before then by printing your lists or saving them as PDFs. Once your organization has moved your mailbox to the cloud, you’ll be able to sign in to To Do and manually reenter the information you saved.

How moving mailboxes from on-premises to Exchange Online affects your To Do data
Microsoft To Do needs an Exchange Online mailbox to store and sync your tasks, which means on-premises mailboxes need to be moved to Exchange Online.

If you use To Do or the Tasks app in Teams with an on-premises mailbox, you’ll lose your To Do data when your on-premises mailbox is moved to Exchange Online. To prepare for that, make sure to either print your lists or save them as PDFs so you can manually recreate them in To Do.

For IT admins at companies with on-premises mailboxes
When you tell employees you’ll be migrating their on-premises mailboxes to Exchange Online, remind anyone who uses Microsoft To Do to print their lists or save them as PDFs.  People who use the Tasks app in Teams will need to download To Do so they can print or save their lists. 

Once you've migrated their mailboxes to Exchange Online, employees will need to manually reenter their saved list information in To Do.

For other employees at companies with on-premises mailboxes
If you use Microsoft To Do or the Tasks app in Teams, your To Do lists and tasks may be lost when your organization migrates its mailboxes from on-premises to Exchange Online. As a precaution, print your To Do lists or save them as PDFs. Once your mailbox has been migrated to Exchange Online, you can manually reenter the information you saved. For more info, talk to your IT admin.

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I work for a Microsoft partner, am currently working on an EXO migration engagement with a customer, and a VIP user just lost all of their To Do Lists/Tasks upon being migrated to EXO.  I hadn't seen the KB article previously, and don't remember seeing anything come through in my Message Center notifications.  When I search the M365 Message Center today, I see nothing about this.

[#2]

We received this in the Message center beginning of this week, together with a list of AAD user GUIDS of impacted users in our tenant.

But the message has now disappeared??

The beginning of the message said:

Microsoft is committed to transparency regarding incidents that affect our customers. As part of this commitment, we’re writing to inform you that a recent misconfiguration inadvertently resulted in the unsupported ability of your users to access Microsoft To Do within your on-premises environment, including Tasks within Teams. This access is unsupported for tenants with on-premises accounts and can cause permanent data loss of To Do lists after performing a migration to Exchange Online mailbox. In efforts to prevent any actual data loss and to mitigate the impact we’ve changed access of Microsoft To Do into a read-only state for your organization on Friday, January 22, 2021 that will last until February 22, 2021. After February 22, 2021, your users will no longer have access to Microsoft To Do, or Teams Tasks permanently as this feature was not intended for use in on-premises environments. During that time, you will need to take the steps outlined below to preserve your data.

[#3]

That is interesting to see. The tenant where I saw this issue had at least one user impacted, and there was no message like this. I wonder how they determine who to notify, and if they purposely retracted the notifications as you experienced.

This wreaks of badness.

[#4]

@Jeremy Bradshaw  Yes it's very fishy. We are now facing the prospective of emailing the whole company as we don't have a list of affected users! Very disappointed in how Microsoft has dealt with this mistake of theirs...

We are in the process of migrating to exchange online, but this is not something we can do overnight!

[#5]

@katherinewilkinson2020 You might have good results using Azure AD Sign-Ins to figure out who all was using To Do while their mailbox resided/resides on-premises.  I had a look in Sign-Ins and found that the Application name can show up as either "Microsoft ToDo....." or "Microsoft To-Do....", so you probably want to filter Application for 'Starts with' = 'Microsoft To'.  I was only able to find traces of the desktop app under Non-interactive sign-ins; everything interactive shows as the web client, though my usage of To Do is minimal, so you might see different results in your tenant.

[#6]

@Jeremy Bradshaw 

Here is is many months after the post you shared and the info is still not accurate.  We're moving to EXO and our employees can use the To Do app on the web.  So will we lose data in O365 as a result of an on prem mailbox being moved?  We do not have the Tasks app in Teams (nor does it appear in the Manage Apps in the Teams admin center).  So do we lose Planner data since employees are using the tab method to access Planner?  Do we lose this data for team tasks or just individual ones?  Is visiting the To Do web app and exporting the data sufficient or is the data lost in Planner too?

So many questions that could have easily been worked through by Microsoft...it's like they don't think to give the communication to an intern/new employee who is removed from their plans to figure out how to keep my data safe.  8-(

[#7]

I have to admit I haven't paid much attention since I posted this originally. It's interesting they can still login while being mailbox-on-premises. Either the dates they published that access would be cut off have slipped or been pushed, or maybe this is indicative of something problematic about your Exchange Hybrid setup. I would open an MS Support request proactively to see what options you have on the table.