Teams error caa70004: what it means and how to fix it

What caa70004 means

The code appears in the bottom-left corner of the Teams sign-in window, usually under We’re sorry, we’ve run into an issue or a similar message. Microsoft’s Teams sign-in help page lists 0xCAA70004 as server or proxy not found. It says the usual causes are a proxy that’s set up wrongly, or a network monitoring tool such as Fiddler that intercepts HTTPS traffic without being set up to decrypt it.

Microsoft’s admin guide to Teams sign-in errors groups caa70004 with problems where the same sign-in failure also affects other Office apps, because Microsoft 365 apps on Windows generally sign in through the same Windows component. If Outlook or OneDrive also fail to sign in, the fixes below still apply.

Classic Teams reached end of availability on July 1, 2025, so this guide covers new Teams. If you’re still seeing the old app, see why Teams classic is gone and how to switch.

Quick test: can Windows reach the sign-in page?

Open Microsoft Edge and go to https://login.microsoftonline.com, then try again in an InPrivate window (Ctrl + Shift + N). Microsoft uses this test for the same sign-in failure in Office: if the page doesn’t load, your network, firewall or security software is blocking it, and Teams can’t sign in either. If it loads fine, the problem is more likely on the PC itself (Fixes 2 to 4).

If Teams can’t connect at all, not just sign in, see Microsoft Teams not connecting.

Fix 1: Check proxy, VPN and inspection tools

1. Disconnect any VPN and try signing in again.
2. Open Settings > Network & internet > Proxy. If Use a proxy server is on and you didn’t set it up, or you’re not on a company network that needs it, turn it off.
3. If you use a debugging proxy such as Fiddler, or a parental-control or ad-blocking tool that inspects HTTPS, close it or turn off HTTPS inspection, then quit and reopen Teams.
4. On a work PC with a company proxy, don’t change these settings yourself; tell IT you’re getting caa70004 so they can check the proxy.

Quit Teams fully before testing: right-click its icon in the notification area and choose Quit, because closing the window only hides it.

Fix 2: Reset new Teams

Microsoft’s cache guide gives two ways to clear new Teams’ local data on Windows:

• Reset: open Settings > Apps > Installed apps, select the three dots next to Microsoft Teams, choose Advanced options and select Reset. This removes the app’s local data, including personal settings, but not your chats, which are stored online.
• Clear the cache folder: quit Teams, then delete the contents of %userprofile%\appdata\local\Packages\MSTeams_8wekyb3d8bbwe\LocalCache\Microsoft\MSTeams.

Start Teams and sign in again. Also check Settings and more > Check for updates once you’re in.

Fix 3: Check the Windows sign-in component

Microsoft 365 apps on Windows use a built-in Windows component, the Microsoft Entra (AAD) broker, to sign in with work or school accounts. If it’s damaged or missing, sign-in fails before Teams can do anything. Microsoft’s authentication guide gives this command to check it and register it again if needed. Save your work first, because it can close running apps, then run it in PowerShell as administrator:

if (-not (Get-AppxPackage Microsoft.AAD.BrokerPlugin)) { Add-AppxPackage -Register "$env:windir\SystemApps\Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy\Appxmanifest.xml" -DisableDevelopmentMode -ForceApplicationShutdown }
Get-AppxPackage Microsoft.AAD.BrokerPlugin

If the last line returns package details, the component is registered. Sign out of Windows and back in, then try Teams. If you see A required authentication broker is missing instead, see how to fix a missing authentication broker.

Some guides tell you to delete the broker’s folders under %localappdata%\Packages. That isn’t Microsoft’s advice and can sign you out of every Microsoft 365 app, so use the command above instead.

Fix 4: Security software

Microsoft says firewalls and antivirus tools mustn’t block the broker (Microsoft.AAD.BrokerPlugin.exe), backgroundTaskHost.exe or login.microsoftonline.com. If you use third-party security software, check its logs or blocked list for those items and add an exclusion, or ask the vendor how. Turning protection off can be a short test, but turn it back on straight away, and don’t leave Windows Firewall disabled.

Other caa codes

The same sign-in page documents these related codes:

Code	What Microsoft says
caa20003	Authorization problem; check the PC’s date and time are correct.
caa20004	Needs approval from the organization; usually a conditional access policy for IT to check.
caa70007	Connection interrupted; check the internet connection and firewall.
caa82ee2, caa82ee7	Request timed out, or the server name couldn’t be resolved; a network or DNS problem.
caa90018	Wrong credentials; your Windows sign-in differs from your Microsoft 365 account. Sign in with the correct work or school email.

Microsoft doesn’t publish meanings for every caa code, so treat explanations of other codes on other sites with caution.

For IT admins

• Run the Teams Sign-in diagnostic in the Microsoft 365 admin center, or the Teams sign-in test in Microsoft Remote Connectivity Analyzer.
• Make sure proxies and firewalls allow the Microsoft 365 URLs and IP ranges and don’t break TLS for login.microsoftonline.com.
• On the affected PC, check Event Viewer under Applications and Services Logs > Microsoft > Windows > AAD > Operational for network errors during sign-in.
• If users see caa20004 instead, review conditional access policies for Teams.

Related guides

• Microsoft Teams not connecting: how to fix it
• A required authentication broker is missing: how to fix it
• Teams classic: why it’s gone and how to switch to new Teams
• How to Remove an Account from Teams (Windows, Phone, Web)
• Teams error 0xCAA82EE2: the request has timed out (how to fix it)

Official sources

• Why am I having trouble signing in to Microsoft Teams? (Microsoft Support)
• Resolve sign-in errors in Microsoft Teams (Microsoft Learn)
• Clear the Teams client cache (Microsoft Learn)