REDUCED_CAPABILITIES_CHATS - Unable to access chats in teams on web/desktop for weeks

Question

REDUCED_CAPABILITIES_CHATS - Unable to access chats in teams on web/desktop for weeks

Cameron Larsen 0

For the last several weeks I have been getting the following error in Teams on web and the desktop app:

[CoreError::REDUCED_CAPABILITIES_CHATS][Error::No data returned for operation `SimpleCollabLeftRailQuery`, got error(s): Sync engine is running in Reduced mode See the error `source` property for more information.]

Slot name:

MID-NAV

Issue occurs on multiple devices (tested from 2 Mac laptops and a windows desktop)
Issue occurs from the web app, chrome, edge, Firefox, and the desktop app
Issue occurs from all networks. We have tested this from my home network, public wifi, and mobile hotspot
the issue occurs on and off VPN

What have we tried already?

password reset
Clearing cache and cookies for all browsers
reinstalling all browsers
clearing cache for teams desktop app
reinstalling teams desktop app
a complete re-image of my laptop
an m365 admin has revoked my active sessions
my teams license was revoked and reinstated after waiting 15 min

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1 answer

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Answer 1

Dear Cameron,

Good day, and I truly appreciate the very detailed breakdown of your issue, along with all the steps you have already taken. I can only imagine how disruptive it must be to lose access to your Teams chats for weeks despite trying so many thorough troubleshooting steps.

Based on what you have described, the REDUCED_CAPABILITIES_CHATS error together with the SimpleCollabLeftRailQuery failure and the "Sync engine is running in Reduced mode" message strongly suggests that this is a tenant or account-side sync issue rather than a client, device, or network problem. Since the behaviour persists across multiple devices, browsers, networks, a full re-image, license reinstatement, and revoked sessions. At this point, the fix will very likely need to come from the Microsoft Support backend rather than from anything further you can do on the client side.

As a forum moderator, I genuinely wish I could sign in to your tenant and inspect the Teams sync engine, mailbox, and chat service state directly to diagnose and fix this for you. Unfortunately, my role here is limited to providing general guidance and solutions that can be applied by users.

I recommend that the Global Admin in your organization create a service request with Microsoft Support. A technical support engineer can perform a remote session to investigate the situation, verify the backend configurations, and run any necessary synchronization tools to resolve the problem. If the issue requires further attention, they can escalate it to a specialized team for deeper analysis. For detailed instructions on how to get support, please refer to Get support - Microsoft 365 admin. If you don't know who your IT administrator is, please refer to this article: How do I find my Microsoft 365 admin? - Microsoft Support

For additional assistance, use this link to find the appropriate contact number from your region: Global Customer Service phone numbers - Microsoft Support

I truly hope you get your issue resolved swiftly. Please know that even though I can't directly intervene, directing you to the correct, specialized support is the most effective help I can provide from my position. Thank you for your patience and understanding. Wishing you all the best.

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