Microsoft Teams Keeps Failing To Send Messages

Harold Wagner 5 Reputation points
2026-08-13T10:30:26.6633333+00:00

This is purely a work-related issue as I don't use Teams anywhere else but I've encountered this multiple times and the issue keeps returning no matter how many times I attempt to fix it.

I will start Teams at the beginning of my shift and it will function just fine (usually), sometimes no problems for the entire shift. Other times, like last night, it will randomly stop sending messages from me. I will still receive messages just fine, but nothing I type (or react) sticks. I should clarify that this mainly affects group chats, and not DMs.

First time I repeatedly got this issue I contacted IT and they reinstalled the whole program and that worked. Then it happened again and I managed to locate where the cache was and delete the whole thing and restart Teams. I did that maybe 2 or 3 times last night.

I suppose my question is, what is causing this issue? What is corrupting the cache, and why is it happening so quickly (multiple times a night)? I don't hate the web version but I'd prefer to get the app fixed, as I find it easier to manipulate and fit within my workspace.

Microsoft Teams | Microsoft Teams for business | Chats | Group chats
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  1. Austin Brock 0 Reputation points
    2026-08-14T14:11:47.8+00:00

    @Harold Wagner I had an issue with Teams doing similar recently, and like you, I could not get it to work no matter what I tried. And I have tried all of the suggestions @Ana Le has provided, to no avail.

    I did find one thing that has potentially stopped this from happening for me, so I'll share my "solution".

    I have my main drive partitioned into an OS drive (C:) and a storage drive (D:) but they are physically the same disk.

    I had low storage on the OS drive due to Docker constantly taking up more and more space. I would have less than a few GB of space left on C: quite often.

    Ever since I freed up space by extending my OS partition and shrinking my data partition, I haven't had the issue ever since. I have 33GB of space free currently.

    I'm not saying this is a fix for you, but if your OS drive is down to a few GB of space, maybe try freeing up some space and see if it stops happening for you too.

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  2. Ana Le 2,225 Reputation points Independent Advisor
    2026-08-13T11:00:36.5733333+00:00

    Hi,

    As the forum's AI recommended, you can first try refreshing/restarting Teams, signing out and back in, testing the same chat in Teams on the web, and resetting or clearing the Teams cache.

    I would add a few points based on the behavior you described:

    • Check Teams on the web while the issue is actually occurring. If you can still send messages and reactions from Teams on the web while the desktop app cannot, this would help narrow the issue down to the desktop client or the local device environment. If the web version is affected as well, the issue may not be related to the local Teams cache.
    • Don't assume that the cache itself is being corrupted. Clearing the cache can temporarily resolve client-side problems by forcing Teams to rebuild its local data, but this does not identify what is causing the problem to recur. Since you have already had to clear the cache multiple times in one night, repeatedly clearing it is unlikely to be a long-term solution.
    • Check the device's network environment if the issue is limited to the desktop app. Because this is a work-managed device, VPN, proxy, firewall, or endpoint security software can potentially interfere with Teams connectivity. Your IT team can check whether anything is affecting Teams connections when the problem occurs.
    • Note whether the issue affects all group chats or only specific ones. Since you mentioned that DMs generally continue to work, knowing whether every group chat is affected or only certain conversations could help determine whether this is a broader client synchronization issue or something specific to particular chats.

    If the issue continues after the above troubleshooting, especially after you have already reinstalled Teams, I would recommend having your Microsoft 365 administrator run the available Teams diagnostics and open a support request if necessary. At that point, further investigation would be more useful than repeatedly clearing the local cache.

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  3. AI answer

    2026-08-13T10:30:45.6433333+00:00

    The repeating pattern points to either a client sync/cache problem in the desktop app or an account/service-side issue if it also starts affecting Teams beyond one local install.

    Based on the symptoms described:

    1. Use the built-in refresh first
      If a banner appears at the top of Teams with a Refresh link, select it. That restarts the app and can restore sync.
    2. Fully restart Teams
      On Windows, right-click the Teams icon in the taskbar and select Quit, then reopen Teams. This is the recommended first step for chat sync and message loading issues.
    3. Check whether the issue is only in the desktop app
      Since the web version is usable, test when the problem happens in the desktop app by opening Teams on the web. If web continues to work while desktop fails, that supports a local desktop client/cache issue.
    4. Sign out and sign back in
      In Teams, select the profile picture at the top right, choose Sign out, then reopen Teams and sign in again.
    5. Clear the full Teams cache, not just part of it
      After quitting Teams:
      • Classic Teams: press Windows key + R, enter %appdata%\Microsoft\Teams, then delete all files and folders in that directory.
      • New Teams: either reset the app in Settings > Apps > Installed apps > Microsoft Teams > More options (...) > Advanced options > Reset, or press Windows key + R, enter %userprofile%\appdata\local\Packages\MSTeams_8wekyb3d8bbwe\LocalCache\Microsoft\MSTeams, then delete all files and folders.
      Warning: resetting New Teams deletes app data, including personalization settings.
    6. Restart Teams after cache clearing
      The first launch can take longer than usual because cache files are rebuilt.

    As for the cause, the available guidance supports that clearing cache can help when Teams has client issues, but it does not identify a specific root cause for “what is corrupting the cache” or why it would recur multiple times in one night.

    Because this has already recurred after reinstalling and repeated cache clears, and because similar persistent messaging issues can be account- or service-side rather than device-side, the next practical step is to have the Microsoft 365 admin open a Microsoft support request. That allows deeper investigation of backend configuration and synchronization issues.

    AI-generated content may be incorrect. Read our transparency notes for more information.

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