Microsoft Teams: "We couldn't connect. Try again."

Hi, it's BlueByte. You open Microsoft Teams, the window loads to a spinner, and it stops on We couldn't connect. Try again. — or the app sits on the loading splash forever, or the sign-in screen shows a code like 0xCAA70007 or 0xCAA20003. Nothing on your machine is broken; Teams just can't finish the handshake it needs to sign you in. We'll walk through what those messages mean, how to tell the causes apart, fix each one with runnable steps, and keep it from coming back.

What "We couldn't connect" and the CAA codes are telling you

Teams shows a few variants of the same story:

We couldn't connect. Try again.
We ran into a problem. Reconnecting…
Status code: 0xCAA70007
Status code: 0xCAA20003

Each one means the client reached a point in sign-in — loading its local state, then asking Microsoft's identity service for a token — and couldn't complete it. The plain We couldn't connect usually points at stale local state; a 0xCAA status code points at the token exchange itself, and the last four hex digits narrow it down. None of them means your account is gone.

The five things that break Teams sign-in

Teams fails to connect for one of these concrete reasons:

• A corrupted local cache — stale tokens and config the client can't reconcile, so it loops on reconnect.
• A wrong system clock — if the date or time is off, TLS to a secure endpoint fails, and Teams reports 0xCAA20003.
• The network or a firewall is blocking the identity endpoints — Teams can't reach login.microsoftonline.com, shown as 0xCAA70007 or 0xCAA82EE2.
• Wrong credentials — the email or password is off, reported as 0xCAA90018.
• A tenant or licensing problem — your admin disabled the app or the subscription lapsed, so no token is issued for you at all.

The first two you fix yourself in a minute. The last three you confirm quickly, then either fix or hand to your IT admin.

First, find out which Teams you're running

The cache path differs between classic Teams and new Teams, so check which one you have before deleting anything:

Get-AppxPackage -Name MSTeams | Select-Object Name, Version

Name     Version
----     -------
MSTeams  <build number, varies by update>

If a line comes back naming MSTeams, you're on new Teams. If the command returns nothing, you're on classic Teams. Note the code shown at the bottom-left of the sign-in screen too — you'll use it below.

Clear the cache to fix stale local state

This is the fix for the plain We couldn't connect loop. Quit Teams fully first — a running process re-locks the files. On classic Teams:

Get-Process -Name Teams -ErrorAction SilentlyContinue | Stop-Process -Force
Remove-Item -Path "$env:APPDATA\Microsoft\Teams\*" -Recurse -Force

On new Teams:

Get-Process -Name ms-teams -ErrorAction SilentlyContinue | Stop-Process -Force
Remove-Item -Path "$env:LOCALAPPDATA\Packages\MSTeams_8wekyb3d8bbwe\LocalCache\Microsoft\MSTeams\*" -Recurse -Force

On macOS, quit Teams (⌘-Q) and clear it from Terminal — classic uses rm -r ~/Library/Application\ Support/Microsoft/Teams; new Teams uses rm -rf ~/Library/Group\ Containers/UBF8T346G9.com.microsoft.teams and rm -rf ~/Library/Containers/com.microsoft.teams2. Nothing here touches your messages or files — those live in the cloud; you're only deleting the local copy Teams rebuilds on the next launch. Restart Teams and sign in; the first start is slower because the cache is being rebuilt.

Fix a clock that's breaking the secure connection

If the code is 0xCAA20003, the machine's clock is off and TLS to Microsoft's endpoints is failing. Resync it:

w32tm /resync

Sending resync command to local computer...
The command completed successfully.

Then confirm the date, time, and time zone are right in Settings. On macOS or Linux, enable automatic time (sudo timedatectl set-ntp true on Linux). A clock more than a few minutes off is enough to break the handshake.

When it's the network, the credentials, or your tenant

For 0xCAA70007 or 0xCAA82EE2, Teams can't reach the identity service. Confirm the endpoint is reachable:

Test-NetConnection login.microsoftonline.com -Port 443

TcpTestSucceeded : True

If that comes back False, a firewall, proxy, or VPN is in the way — work with your IT admin to allow the Microsoft 365 endpoints. For 0xCAA90018, sign in again with the correct email and password. And if no one in your organization can sign in, or the code maps to a disabled app, that's a tenant or licensing issue only your admin can clear — note the exact status code and send it to them.

A real case: classic Teams stuck on the spinner

A user's classic Teams opens to the loading spinner and lands on We couldn't connect. Try again. The clock is correct and other apps reach the internet, so it's local state. Get-AppxPackage -Name MSTeams returns nothing, confirming classic Teams. You quit it, run the two classic-Teams commands above to clear %APPDATA%\Microsoft\Teams, and relaunch. The first start takes about twenty seconds while the cache rebuilds, then sign-in completes and Teams stays connected. The account and data were fine the whole time — only the local cache was wedged.

Confirm Teams signs in and stays connected

After the fix, Teams should reach your chat list and stay there, not bounce back to Reconnecting…. Send yourself a message and reload; if it persists and presence shows you online, sign-in is healthy. If it still can't connect, re-read the status code — a different code means a different cause on this list, not a failed cache clear.

Keep it from coming back, and how it differs from Outlook not starting

Let new Teams update itself rather than pinning an old build, keep the system clock on automatic time, and quit Teams cleanly instead of killing it mid-write so the cache isn't left half-written. This is a different failure from Outlook's Cannot start Microsoft Outlook — that one is a broken local profile or OST and is fixed by repairing the profile, not by clearing a Teams cache. Both are local-state problems, but they live in different apps and different folders. Next time Teams won't connect, read the status code first, then walk this list from cache to clock to network.