Exchange Backend Mailbox Sync Stall - Account Level Issue

Question

Exchange Backend Mailbox Sync Stall - Account Level Issue

StaceyLutz-4397 5

I have performed all client-side resets. The issue persists across Web, iOS, and Desktop. I need a backend escalation to reset my Exchange Online sync index. this has been going on for over two weeks. Every time I attempt to get help through support, I get routed around in a circle and nothing happens. I use the to-do app specifically only through the app which I got through the Apple App Store. I am using an iPhone 17 with iOS 26.2. The app has become completely useless to me and I have hundreds of tasks. I do not use Outlook.

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Answer 1

Jayden-P 4,225 Independent Advisor

Please note that this forum is not Microsoft support, this is a user-to-user support forum. Therefore, I cannot directly escalate this for you.

Hi @StaceyLutz-4397

Since the issue is reproducible across Web, iOS, and Desktop, it suggests the problem may not be isolated to a specific device or app installation. If the task data is not displaying correctly in the web version as well, that would mean the issue is likely tied to the account's synchronized task data rather than a local client.

You mentioned having hundreds of tasks, but you also indicated that the issue persists across Web, iOS, and Desktop.

To better understand the situation, how are you determining that those tasks still exist?

When you access Microsoft To Do on the web, do you see any of the tasks?
Are the tasks completely missing, or are they visible but not syncing correctly between devices?
Do you have screenshots, exports, notifications, or another source that shows the tasks are still present?

I'm asking because if the same behavior occurs across all clients, including the web app, then all clients are reading from the same underlying service data. Understanding where you're seeing the "hundreds of tasks" will help clarify whether this is a synchronization issue, a data visibility issue, or something else.

Are you signed in with a personal Microsoft account (Outlook.com, Hotmail.com, Live.com) or a work/school Microsoft 365 account? Your account type will determine the appropriate support path.

If you're using a personal Microsoft account, please contact Microsoft Consumer Support through https://support.microsoft.com/home/contact
If you're using a work or school Microsoft 365 account, please contact your organization's Microsoft 365 administrator, as they can open a support request with Microsoft on behalf of the tenant.

StaceyLutz-4397 5 Reputation points

2026-11-01T12:45:14.64+00:00
Hi Jayden,

Thanks for your response. To answer your questions:

Account Type: I am using a personal Microsoft account (registered under a Yahoo email address).

Where the tasks exist: The task lists are visible locally on my primary iPhone app, but my phone explicitly alerts me that I have unsynced local data that will be lost if I sign out. When I log in via the Web version, the missing items do not sync over. This all started because I noticed that suddenly some of my tasks were missing across all platforms. Many are still there, but not all.

The Core Issue: This is an active sync failure between the local app cache and the Exchange server. Standard troubleshooting (signing out) is not an option because it will delete the local unsynced data.

Since standard consumer support forms loop continuously without connecting to a human agent, how can an Exchange Online backend sync reset be requested for a personal account in this state?

I have used to do, downloaded on my iPhone 17, using iOS 27.2 now, for years. Literally since it was the Wunderlist app and Microsoft purchased it. While I have a Microsoft 365 personal account, that came along much later.

When I go into the Microsoft to-do app and perform a manual sync it says everything syncs correctly. But it doesn’t because the missing tasks do not reappear. If I don’t sign out, but delete and re-download the app it still has the same problem. If I attempt to sign out of the app, I get the following message “Are you sure you want to sign out? You have unsynced data which will be lost if you sign out. Try syncing manually, or contact support.”

The problem is, there is no support option through the app, at all. So I end up in a never-ending loop on the Microsoft site trying to find a contact for assistance and ending up with self-help tools that don’t help. I actually got to a live person once in chat who said they couldn’t help me (even though I got there via links for To Do help) and sent me to help for Outlook, which also did not help because I don’t have or use an Outlook email address, I only use Yahoo. It’s been massively frustrating so that’s why I ended up here. Just trying to find anything that will get me to someone who can help me fix this. Thanks again for responding at all.
Jayden-P 4,225 Reputation points Independent Advisor

2026-11-01T13:56:39.3466667+00:00

As you are using a personal account, another appropriate team will engage to assist you further with this issue.

Answer 2

Ian-T 15,605 Microsoft External Staff Moderator

Hi @StaceyLutz-4397

I understand why you do not want to sign out. Since the iPhone still contains unsynced tasks, signing out, resetting, or reinstalling the app could permanently remove that local data. Microsoft’s troubleshooting guidance also warns against signing out when unsynced data remains.

Because the problem affects the app and the web version, further device-level resets are unlikely to provide a safe solution. Unfortunately, forum moderators cannot inspect your account’s Exchange Online task data or request a backend sync-index reset.

The only supported escalation route is Microsoft To Do support. The current instructions are to open To Do, select your profile name, then Help & Feedback > Get support, and use the in-app messaging option. If that option is missing or inaccessible, try the support link shown in Microsoft’s sync-error guidance and clearly state:

“My personal Microsoft account has unsynced local To Do data that will be lost if I sign out. The issue also occurs on To Do Web. Please preserve the local data and escalate this as an account-side Microsoft To Do/Exchange Online synchronization issue.”

Until the case reaches the appropriate support team, avoid signing out, reinstalling, resetting the app, or deleting its local data.

Thank you for your understanding and time

StaceyLutz-4397 5 Reputation points

2026-11-02T02:56:49.3666667+00:00

Thank you, but you’ve basically just put me back into the loop I’ve been already going through for the last couple of weeks. I’ve already indicated there is no support option in the Microsoft To Do app, which I got through the Apple App Store, many years ago. Also, going online through the Microsoft support and selecting to do as I said in my previous note does not actually get me to anyone who can help. When I finally actually got to a live person to chat, they said they could not help me and sent me to an Outlook support queue, which also then couldn’t help me because I don’t have an Outlook email address. My account is through Yahoo, which is my Apple ID. This is just impossible. I cannot believe that support is so terrible.
Ian-T 15,605 Reputation points Microsoft External Staff Moderator

2026-11-02T03:19:55.2533333+00:00

You’re absolutely right, and I’m sorry my previous reply sent you back through the same support loop you had already described. I understand that the in-app support option is not available, and that both the general support and Outlook routes have already failed to connect you with someone who can investigate the To Do sync issue.

Unfortunately, this community cannot access your account or the To Do backend to perform the reset you need. I don’t want to keep repeating support options that you have already exhausted. Please continue avoiding signing out or reinstalling the app while those unsynced tasks remain on your iPhone. I’m genuinely sorry that there is no useful escalation path I can give you from here, especially after the amount of effort you have already put into trying to get help
StaceyLutz-4397 5 Reputation points

2026-11-02T04:32:32.6633333+00:00

OK, so I think what you’re saying is there’s nothing else I can do to try to recover my data. There’s no other possible escalation path and I basically need to find another app and hope I can remember the tasks that I’m missing?
Ian-T 15,605 Reputation points Microsoft External Staff Moderator

2026-11-02T05:04:22.5366667+00:00

I understand why it sounds that way, and I’m sorry this has been so frustrating. I don’t want to make a definite conclusion about the missing tasks or suggest that you should give up on them. For now, the safest step is to preserve everything still visible on your iPhone and avoid signing out, resetting, or reinstalling the app while unsynced data remains.
Hornblower409 18,575 Reputation points

2026-11-03T10:14:59.1633333+00:00
@StaceyLutz-4397 said

There’s no other possible escalation path

Not that I can find.

To Do App support link - No

To Do Web support link - No

support.microsoft.com product routing - Does not recognize To Do or any variations

All I can come up with is a "Support" link on the App Store listing
https://apps.microsoft.com/detail/9nblggh5r558
And that is just a mailto: [email protected]

Give it a try?
Ian-T 15,605 Reputation points Microsoft External Staff Moderator

2026-11-04T05:58:59.31+00:00

Thank you Hornblower409 for the additional comment
StaceyLutz-4397 5 Reputation points

2026-11-04T06:17:38.2733333+00:00

Thank you so much everyone for trying to come up with ideas to assist me, I really do appreciate it! I do realize this is a user forum, I just was hoping that someone else had experienced a similar issue and had any kind of idea that could help me. At this point, I think my only option after weeks of trying to resolve this is to just migrate to a more reliable service that actually has support, and hope I can figure out my missing tasks or that they miraculously somehow appear at some point in my To Do app. I wish you all the very best and again thank you for trying to help.
Ian-T 15,605 Reputation points Microsoft External Staff Moderator

2026-11-04T06:18:46.6533333+00:00

Thank you for your time, have a nice day