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0xCAA50021

Microsoft 365 0xCAA50021 in Teams and Office: activation error

Verified with sources6 sourcesReviewed Oct 18, 2026
Technician coming? See the 2 steps they must show you

Risk level

Medium

Proceed carefully and stop if the check is unclear.

Urgency

Medium

Quick answer

Code 0xCAA50021 appears when activating or signing in to Microsoft 365 apps and Teams. Remove any MicrosoftOffice16 entries in Windows Credential Manager, disconnect the work or school account in Settings if it differs from your Windows login, and restart.

Safety first

Stop and check this first

  • On a managed work or school PC, do not disable antivirus, proxy, firewall or VPN software yourself without checking with your system administrator regarding Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy.
  • Several 0xCAA50021 fixes require a Microsoft 365 administrator account; always record the status code from the sign-in window before contacting IT.

Safe checks you can perform

  • Remove MicrosoftOffice16 credentials and check Access work or school
  • Delete TokenBroker\Accounts cache files and run the troubleshooter
  • Check Microsoft Entra ID join status with dsregcmd /status

Leave these tasks to a qualified professional

  • Do not attempt this professional task: Refresh user license and enable device registration in Entra ID
  • Do not attempt this professional task: Reset activation state or leave and rejoin Microsoft Entra ID

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. Refresh user license and enable device registration in Entra ID

    What they doA Microsoft 365 administrator checks Users > Active users > Licenses and Apps in the Microsoft 365 Admin Center (unchecking, saving, re-checking and saving the license if already assigned) and confirms in the Microsoft Entra admin center (Identity > Devices > All devices > Device settings) that Users may join devices and Users may register their devices are set to All.

    They must show youyour active license assignment and the Microsoft Entra ID Device settings set to All.

    In writingwhich license was refreshed and whether proxy, firewall or antivirus rules were updated to allow Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy.

  2. Reset activation state or leave and rejoin Microsoft Entra ID

    What they doUsing administrator privileges, IT support resets the Microsoft 365 Apps activation state or opens an elevated Command Prompt, runs dsregcmd /leave, confirms AzureAdjoined is NO, restarts the PC, and rejoins the device to Microsoft Entra ID.

    They must show youdsregcmd /status showing AzureAdjoined: YES after rejoining and Microsoft 365 activating cleanly.

    In writingthe recovery steps performed on the device join state and, if escalated to Microsoft Support, the support request number and debug logs collected.

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. Remove MicrosoftOffice16 credentials and check Access work or school

    No special tools

    Who:
    you.
    How:
    open Credential Manager from Start, choose Windows credentials, and select Remove on any MicrosoftOffice16 entries; then open Settings > Accounts > Access work or school, and if your office.com account is listed there but is not the account you use to sign in to Windows, select it, choose Disconnect, and restart the device.
    Result that matters:
    clearing stale Office credentials and mismatched work account bindings before retrying activation or sign-in.
    If Microsoft 365 or Teams signs in and activates after the restart:
    cached credentials caused the conflict.
    If ERROR:
    0xCAA50021 comes back: move on to clearing the TokenBroker cache and checking dsregcmd.
    Evidence to keep:
    screenshot of Access work or school and note of the removed MicrosoftOffice16 credentials.

    Evidence: Microsoft 365 Apps activation error 0xCAA50021

  2. Delete TokenBroker\Accounts cache files and run the troubleshooter

    No special tools

    Who:
    you.
    How:
    open File Explorer, go to %LOCALAPPDATA%\Packages\Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy\AC\TokenBroker\Accounts, press Ctrl + A and delete all files; do the same in %LOCALAPPDATA%\Packages\Microsoft.Windows.CloudExperienceHost_cw5n1h2txyewy\AC\TokenBroker\Accounts, restart the device, and run the Microsoft 365 sign-in troubleshooter in Get Help.
    Result that matters:
    forcing the work and personal token broker plug-ins to rebuild their account cache.
    If the Get Help sign-in troubleshooter completes sign-in without 0xCAA50021:
    the local TokenBroker data was corrupt.
    If the error persists:
    a firewall/proxy may be blocking BrokerPlugin or an admin setting in the tenant needs attention.
    Evidence to keep:
    result screen from the Microsoft 365 sign-in troubleshooter in Get Help.

    Evidence: Microsoft 365 Apps activation error 0xCAA50021

  3. Check Microsoft Entra ID join status with dsregcmd /status

    No special tools

    Who:
    you, in Command Prompt.
    How:
    open Command Prompt, run dsregcmd /status, and note whether AzureAdjoined reads YES or NO along with the exact status code shown on the sign-in window.
    Result that matters:
    giving your IT administrator the exact device registration state for Microsoft Entra ID troubleshooting.
    If AzureAdjoined or device state shows an issue:
    send the dsregcmd /status output and code 0xCAA50021 to your IT admin.
    If local status looks normal but multiple Office apps fail:
    IT must check proxy/firewall rules and license assignment.
    Evidence to keep:
    screenshot of the dsregcmd /status output and the 0xCAA50021 error screen.

    Evidence: Why am I having trouble signing in to Microsoft Teams? · Microsoft 365 Apps activation error 0xCAA50021

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

  • 0xCAA50021
  • activation error 0xCAA50021
  • CAA50021
  • error de activación 0xCAA50021
  • ERROR: 0xCAA50021
  • Microsoft 365 0xCAA50021
  • Office 0xCAA50021
  • Teams 0xCAA50021

What it means

In Microsoft Learn's troubleshooting guide for Microsoft 365 Apps and Teams sign-in documentation, ERROR: 0xCAA50021 points to conflicting cached Office credentials, a blocked or corrupted Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy token broker, an unassigned user license, or disabled device registration in Microsoft Entra ID. Behavior can differ across cloud environments or versions, and the code alone never proves your device, account or service is faulty.

Warnings and stop conditions

  • Mediumeditorial warning

    On a managed work or school PC, do not disable antivirus, proxy, firewall or VPN software yourself without checking with your system administrator regarding Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy.

    Evidence: Microsoft 365 Apps activation error 0xCAA50021

  • Loweditorial warning

    Several 0xCAA50021 fixes require a Microsoft 365 administrator account; always record the status code from the sign-in window before contacting IT.

    Evidence: Why am I having trouble signing in to Microsoft Teams? · Microsoft 365 Apps activation error 0xCAA50021

Symptoms and causes

Probable causes · in order

  • Conflicting MicrosoftOffice16 credentials or work account linkCommon

    Stored MicrosoftOffice16 entries in Windows Credential Manager or an office.com account connected under Access work or school that differs from the Windows sign-in account block token validation.

    Evidence: Microsoft 365 Apps activation error 0xCAA50021

  • Blocked BrokerPlugin process or corrupted TokenBroker cachePossible

    Antivirus, proxy, firewall or VPN software blocks Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy, or cached files under TokenBroker\Accounts need to be cleared.

    Evidence: Microsoft 365 Apps activation error 0xCAA50021

  • Unassigned license or disabled device registration in Entra IDPossible

    The user account lacks an active license in the Microsoft 365 Admin Center, or Device settings in Microsoft Entra ID prevent users from joining or registering devices.

    Evidence: Why am I having trouble signing in to Microsoft Teams? · Microsoft 365 Apps activation error 0xCAA50021

Virtual technician

Does 0xCAA50021 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

    Resolución de errores de inicio de sesión en Teams

    Microsoft · 2025 · official_doc

  3. 3

    Why am I having trouble signing in to Microsoft Teams?

    Microsoft · 2026 · official_doc

  4. 4

    ¿Por qué tengo problemas para iniciar sesión en Microsoft Teams?

    Microsoft · 2026 · official_doc

  5. 5

    Microsoft 365 Apps activation error 0xCAA50021

    Microsoft · 2026 · official_doc

  6. 6

    Error de activación de Aplicaciones de Microsoft 365 0xCAA50021

    Microsoft · 2026 · official_doc

Sources: Fix Teams sign-in errors · Resolución de errores de inicio de sesión en Teams · Why am I having trouble signing in to Microsoft Teams? · ¿Por qué tengo problemas para iniciar sesión en Microsoft Teams? · Microsoft 365 Apps activation error 0xCAA50021 · Error de activación de Aplicaciones de Microsoft 365 0xCAA50021reviewed 2026-10-18 · verified

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