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0xCAA70004

Microsoft 365 0xCAA70004 in Teams: server or proxy not found

Verified with sources3 sourcesReviewed Oct 3, 2026
Technician coming? See the 3 steps they must show you

Risk level

Medium

Proceed carefully and stop if the check is unclear.

Urgency

Medium

Quick answer

Teams shows 0xCAA70004 because it could not find the server or proxy. It is usually a misconfigured proxy or a program intercepting network traffic. Send the code to your IT admin.

Safety first

Stop and check this first

  • Do not turn off the company proxy or antivirus yourself to test: IT corrects the configuration.

Safe checks you can perform

  • Programs intercepting the network
  • Whether other Office apps fail too
  • Teams client update
  • Report the code to IT support

Leave these tasks to a qualified professional

  • Do not attempt this professional task: Check device and network proxy
  • Do not attempt this professional task: AAD Operational log and token processes
  • Do not attempt this professional task: Teams Sign-in diagnostic

What a technician must be able to justify

Technician visit

These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.

These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.

  1. Check device and network proxy

    What they doThe IT technician checks the proxy settings and stops or correctly configures the network sniffing program before relaunching Teams.

    They must show youthe proxy configuration found.

    In writingwhat was corrected.

  2. AAD Operational log and token processes

    What they doThe technician opens Event Viewer, Applications and Services Logs, Microsoft, Windows, AAD, Operational, and checks that firewall and antivirus do not block Microsoft.AAD.BrokerPlugin.exe or backgroundTaskHost.exe, and that the network does not block login.microsoftonline.com.

    They must show youthe error entries in the AAD log.

    In writingwhich process or destination was blocked and the exception applied.

  3. Teams Sign-in diagnostic

    What they doThe Microsoft 365 administrator runs the Teams Sign-in diagnostic in the admin center with the user's email, or the Teams Sign in test in the Microsoft Remote Connectivity Analyzer.

    They must show youthe test results.

    In writingthe issue found and the fix applied.

Before accepting a part or repair

Nothing has been shown yet. Do not accept a part swap based on the code alone.

Follow these steps

Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.

  1. Programs intercepting the network

    No special tools

    Who:
    you.
    How:
    if you use network analysis or debugging tools (for example Fiddler), close them and reopen Teams. If you do not know whether one is present, do not uninstall anything: hand it to IT.
    Result that matters:
    whether Teams signs in once that tool is closed.
    If it does:
    the tool was intercepting HTTPS unconfigured.
    If you use none or nothing changes:
    check other Office apps.
    Evidence to keep:
    name of the tool closed and the result.

    Evidence: Why am I having trouble signing in to Microsoft Teams?

  2. Whether other Office apps fail too

    No special tools

    Who:
    you.
    How:
    try signing in to Outlook or Word with the same account and note whether they error.
    Result that matters:
    whether the failure is Teams only or all of Office.
    If all of Office fails:
    IT should check Office sign-in on Windows (AAD log and blocks).
    If only Teams fails:
    update and reinstall Teams.
    Evidence to keep:
    list of failing apps and codes.

    Evidence: Fix Teams sign-in errors · Connection issues when signing in after updating to Office 2016 build 16.0.7967 on Windows 10

  3. Teams client update

    No special tools

    Who:
    you.
    How:
    in Teams, open the Settings and more menu next to your profile picture at the top right and select Check for updates. Install anything offered and sign in again.
    Result that matters:
    whether 0xCAA70004 goes away on the latest version.
    If you get in:
    the client was missing the latest update.
    If it repeats:
    go to the next check.
    Evidence to keep:
    Teams version before and after.

    Evidence: Fix Teams sign-in errors

  4. Report the code to IT support

    No special tools

    Who:
    you.
    How:
    note the status code at the bottom left of the window (0xCAA70004), the time and whether other Office apps fail too, and send it to your IT admin.
    Result that matters:
    IT getting the exact code.
    If IT finds the cause in the tenant or network:
    they fix it on their side.
    If not:
    IT opens a support request with Microsoft including debug logs.
    Evidence to keep:
    screenshot of the sign-in screen with the code.

    Evidence: Fix Teams sign-in errors · Why am I having trouble signing in to Microsoft Teams?

Still not solved

If the error persists, stop here. See what the technician must do and show you.

Where this code applies

A code is meaningful only inside the right product and version context.

Primary scope

System
Software and digital services
Brand
Microsoft 365
Product type
Office suites

Known code variants

  • CAA70004
  • código de estado caa70004
  • Teams 0xCAA70004

What it means

Microsoft explains that 0xCAA70004 means the server or proxy was not found, usually because a proxy is misconfigured or a network sniffing program such as Fiddler is running without being set up to decrypt HTTPS. If the failure also appears in other Office apps, Microsoft points to the Office sign-in connection issues article (WAM). The code does not say which network element causes it.

Warnings and stop conditions

  • Loweditorial warning

    Do not turn off the company proxy or antivirus yourself to test: IT corrects the configuration.

    Evidence: Why am I having trouble signing in to Microsoft Teams?

Symptoms and causes

Probable causes · in order

  • Misconfigured proxyCommon

    Happens on proxied networks or after a proxy change. IT confirms it by checking the device proxy.

    Evidence: Why am I having trouble signing in to Microsoft Teams?

  • Network sniffing program intercepting HTTPSPossible

    Tools like Fiddler running unconfigured. Goes away when closed and Teams restarted.

    Evidence: Why am I having trouble signing in to Microsoft Teams?

  • Firewall or antivirus blocking Office sign-inPossible

    The failure also shows in Word, Outlook or other Office apps.

    Evidence: Fix Teams sign-in errors · Connection issues when signing in after updating to Office 2016 build 16.0.7967 on Windows 10

Virtual technician

Does 0xCAA70004 still appear after these checks?

Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.

Start diagnosis

Sources and technical references

  1. 1

    Fix Teams sign-in errors

    Microsoft · 2025 · official_doc

  2. 2

    Why am I having trouble signing in to Microsoft Teams?

    Microsoft · 2026 · official_doc

  3. 3

    Connection issues when signing in after updating to Office 2016 build 16.0.7967 on Windows 10

    Microsoft · 2025 · official_doc

Sources: Fix Teams sign-in errors · Why am I having trouble signing in to Microsoft Teams? · Connection issues when signing in after updating to Office 2016 build 16.0.7967 on Windows 10reviewed 2026-10-03 · verified

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