Teams 2.0 Errors and the Classic Teams Retirement: What’s Actually Different

Classic Teams — the Electron-based desktop client most people had been using since 2017 — was retired on July 1, 2025. By that date, users had to be on the new Teams (sometimes called “Teams 2.0,” “Teams 2.x,” or just “the new Teams”) or they could not sign in. There is no transition period left to talk about. The interesting story now is that the troubleshooting playbook for Teams has quietly become a different document, and most of the support content on the open web is still telling you to do things that no longer apply.

This page is about what actually changed, what error patterns are now common in the new Teams that did not exist in classic, and the diagnostic steps that do work in 2026 versus the ones that are leftover from the old client.

What changed under the hood

Classic Teams was an Electron application — Chromium plus Node.js, packaged into a desktop shell. It stored its profile data in %appdata%\Microsoft\Teams, ran web rendering through its bundled Chromium runtime, and shipped roughly twice the memory footprint of its underlying browser engine.

The new Teams is built on WebView2 and packaged as MSIX. The architectural change is consequential:

AspectClassic Teams (retired)New Teams
RuntimeBundled Chromium / ElectronWebView2 (system-shared Edge engine)
PackagingSquirrel installerMSIX package
User profile path%appdata%\Microsoft\Teams\%localappdata%\Packages\MSTeams_*\
Memory footprintHigh~50% lower per Microsoft’s own benchmarks
Add-in modelCustom Teams app SDKSame SDK, runs in WebView2
Install methodPer-user automaticMSIX, installed per machine via Group Policy or per user

The shared WebView2 runtime is the mechanical reason the new Teams uses less memory — it is leveraging the Edge engine that is already on the system rather than shipping its own. It is also the reason new categories of error have appeared: anything that breaks WebView2 (corrupted installation, group policy conflicts, AllowAllTrustedApps disabled at the OS level) now breaks Teams in ways that classic Teams did not see.

This is a larger point worth understanding. Most Teams troubleshooting content on the web — and most of what users find when they search for an error — was written for the classic client. The standard “delete everything in %appdata%\Microsoft\Teams and restart” advice does nothing for new Teams because new Teams does not store its data there. If you have been reaching that step on a new Teams problem and finding that it does not help, that is why.

Where new Teams stores its state

The new Teams MSIX package puts its user data in:

%localappdata%\Packages\MSTeams_8wekyb3d8bbwe\

The 8wekyb3d8bbwe is the Microsoft Store package identifier; it is the same on every Windows install. Inside that directory, the relevant subfolders are:

  • LocalCache\Microsoft\MSTeams\ — cached UI assets, settings, and authentication tokens
  • LocalState\ — local state, including user preferences
  • Settings\ — settings.dat and similar

Clearing the new Teams cache the right way means:

  1. Right-click the Teams icon in the system tray, click Quit (not just close the window).
  2. Open File Explorer, paste %localappdata%\Packages\MSTeams_8wekyb3d8bbwe\LocalCache into the address bar.
  3. Delete the contents (skip any files that report as in use).
  4. Restart Teams.

This procedure is the new equivalent of the old %appdata%\Microsoft\Teams cache wipe. It resolves a meaningful subset of the issues that the classic procedure used to fix: stale authentication, corrupted UI cache, missing or outdated profile pictures, search and presence inconsistencies, and what Cornell IT’s Teams troubleshooting page describes as “general slowness.”

The error code surface that is still working

Many of the underlying error codes are the same between classic and new Teams because they originate in the Microsoft Identity platform rather than in the client. The codes most often seen in the new client are:

CodeCauseFirst-line fix
0xCAA20003Authorization problem — date/time misconfiguredSync Windows time, restart Teams
0xCAA82EE2Request timed outCheck internet connection and firewall
0xCAA82EE7Server not resolvedDNS issue; ipconfig /flushdns, check VPN
0xCAA20004Request requires admin approvalTenant admin must approve the app
0xCAA90018Incorrect credentialsSign out fully, sign back in
0xCAA5004BUnexpected app issueWait, retry, or use Teams Web
CAA50021Sign-in retry threshold exceededSee our CAA50021 hub
0x80090016TPM-related sign-in failureSee the dedicated guide

The pattern most users are not seeing: many of these errors occur in both Teams and other Microsoft 365 apps because they originate from the Entra ID (formerly Azure AD) authentication layer rather than from Teams specifically. If you see CAA50021 in Teams, the same error will likely show up in Outlook and OneDrive on the same device. Treating it as a Teams problem leads to the wrong fixes; treating it as an Entra sign-in problem leads to the right ones.

The new Teams error patterns that are genuinely new

Several failure modes are specific to the new client and did not exist in classic:

“Due to org policy, you can’t install the new Teams.” This is an MSIX installation block triggered by Group Policy or third-party security tools restricting the installation of trusted apps. The most common underlying registry block is AllowAllTrustedApps set to disabled. Microsoft published a fix for this in the Windows October 2023 cumulative update (KB5031455 for Windows 11, KB5031445 for Windows 10) — the November 2023 security update also includes the fix. If you are seeing this error in 2026, your Windows is missing several years of cumulative updates and the Teams install is not the priority — fix the Windows Update state first.

“Something went wrong” on first launch after toggling from classic. This is the launch_pear_app failure documented in Microsoft Learn’s troubleshooting reference. The cause is almost always one of: Cookies or Cache shell folders pointing to a reparse point, TEMP/TMP environment variables pointing to a reparse point, missing Read permissions on AppData folders, or invalid files in AppData with the same name as required system folders. The fix involves checking and updating the User Shell Folders registry keys; Microsoft publishes a PowerShell diagnostic script at the Resolve issues when starting the new Teams app page.

WebView2 missing or corrupted (Windows 10). Windows 10 does not include WebView2 in the base OS image; it ships separately. Windows 10 users installing new Teams may receive a WebView2 dependency error and need to install the WebView2 Runtime from Microsoft directly. On Windows 11, WebView2 is included; this category of error is Windows 10-specific.

Unicode/path-length issues with profile redirection. Several enterprise environments use folder redirection to redirect AppData to network shares. The MSIX architecture has different requirements than the old Squirrel installer for AppData paths, and folder redirection that worked perfectly with classic Teams can produce sign-in loops or cache corruption with new Teams. The fix is excluding the new Teams package paths from folder redirection, which is documented but not widely published.

Tenant-level Auto Update disabled. Some enterprise tenants disabled automatic updates for classic Teams to control rollout. New Teams updates through MSIX and the Microsoft Store update mechanism, which is different from the classic Teams updater. Tenants that have not adjusted their endpoint update policies are now sitting on outdated new Teams versions and seeing intermittent server-side compatibility errors that resolve only with a manual update.

Cache clearing — the right procedure

If you are landing on this page because Teams is stuck loading, won’t let you sign in, or is showing presence/search bugs, the cache clear procedure for new Teams is:

  1. Right-click the Teams icon in the system tray and select Quit. Wait 10 seconds.
  2. Confirm Teams is fully closed via Task Manager (Ctrl+Shift+Esc; check for “Microsoft Teams” entries).
  3. Hold the Windows key and press R. Type or paste: 
    %localappdata%\Packages\MSTeams_8wekyb3d8bbwe\LocalCache
    Press Enter.
  4. Select all files and folders in this directory and delete them. Skip any that are in use.
  5. Restart Teams. Sign in again.

This procedure resolves the bulk of “Teams is acting weird” issues without affecting your installed configuration, your tenant settings, or your saved data (which lives in Microsoft 365 services, not in the local cache).

If the cache clear does not resolve the issue, the next step is to repair or reinstall the MSIX package:

Get-AppxPackage *MSTeams* | Reset-AppxPackage

Run that in elevated PowerShell. It will reset the package without uninstalling. If that fails:

Get-AppxPackage *MSTeams* | Remove-AppxPackage

Then reinstall from teams.microsoft.com/downloads. This is destructive in the sense that any local-only state is lost, but Teams stores almost nothing locally that matters — your chats, files, and meetings are in the cloud.

Classic Teams remnants you might still see

Several artifacts from classic Teams persist on machines that were upgraded rather than freshly imaged:

  • Shortcuts pointing to the old install path. %localappdata%\Microsoft\Teams\Update.exe shortcuts will fail; redirect to the new MSIX-installed Teams or recreate them from the Start menu.
  • Stale registry keys. HKCU\Software\Microsoft\Office\Teams may contain settings from the classic client. These are mostly harmless; do not delete them unless you have a specific issue tied to a documented registry value.
  • Outlook integration. Classic Teams had a separate Outlook plugin (Microsoft Teams Meeting Add-in); new Teams uses a different integration mechanism (Outlook web add-in for new Outlook, COM-based add-in for classic Outlook). On machines that have both old and new Teams add-ins registered in Outlook, calendar entries can show duplicate “Join Teams Meeting” buttons. Removing the old Microsoft Teams Meeting Add-in via Outlook → File → Options → Add-Ins fixes this.

When to stop

If Teams is not signing in and the standard cache-clear procedure has not worked, the failure mode worth knowing about is Conditional Access blocking the new Teams app registration. Some organizations have Conditional Access policies that target specific application IDs; the new Teams has a different application ID than the classic client, and a policy that allowed classic but does not explicitly allow new Teams will block sign-in. The error appears as a generic sign-in failure rather than a clear “blocked by policy” message. The fix is at the tenant level — IT administrators need to update Conditional Access policies to include the new Teams application — and is not something an end user can resolve.

This is also the point where the right answer is to stop diagnosing and contact your IT administrator. New Teams sign-in failures in managed environments are increasingly tenant-side rather than client-side, and end-user troubleshooting cannot fix tenant-side configuration. The 30-minute time investment in a thorough local clean-and-reinstall is reasonable; beyond that, the diagnostic value drops sharply.

If Teams is loading but specific features are broken (calendar not syncing, search returning empty results, presence stuck), see the dedicated stuck-on-loading guide. If you are seeing the TPM-related 0x80090016 error, the TPM error guide covers the device-attestation chain that needs to be working.

A category of bad advice that has spread on YouTube and lower-quality forum sites: do not run “Teams cleanup tools” or “Microsoft Teams uninstall and reinstall scripts” downloaded from third-party sites. Microsoft’s own tooling is sufficient for any legitimate diagnostic step. Third-party Teams “fixers” are uniformly suspicious and several have been documented as malware vectors.

The pattern

The classic-to-new Teams transition is the cleanest example of a forced-rollout migration that has actually concluded. Unlike the new Outlook situation — where Microsoft keeps slipping the deadline — Teams classic is genuinely retired. There is no fallback. Users who try to launch classic Teams in 2026 are redirected to the new client.

What that means for the support content surface: the next 12-24 months will produce a steadily growing gap between accurate, current Teams diagnostic guidance and the legacy support content that was written for classic. Users searching for Teams error codes will find a mix of accurate-for-classic, accurate-for-new, and accurate-for-both content. Filtering for current relevance is the editorial work that matters here, not generating more error code coverage.

If you are bookmarking diagnostic resources for new Teams: the Microsoft Learn troubleshooting hub at learn.microsoft.com/microsoftteams/troubleshoot/ is the authoritative source. Several of its individual pages have been updated for new Teams architecture; others are still classic-era documentation. Check the “Last updated” date on each page before relying on its procedure.

FAQ

Is classic Teams still available? No. Microsoft retired classic Teams (1.0) on July 1, 2025. Classic Teams cannot sign in to Microsoft 365 services anymore; users are redirected to download new Teams. If you see “classic Teams” still installed somewhere, it is either a leftover artifact or a managed environment that pinned the old version locally — but it cannot connect to Microsoft 365.

Why is the cache clear not fixing my Teams issue like it used to? You may be deleting the wrong directory. Classic Teams stored its cache in %appdata%\Microsoft\Teams. New Teams stores it in %localappdata%\Packages\MSTeams_8wekyb3d8bbwe\LocalCache. The procedure is similar but the path is different.

Can I install both classic and new Teams? Not anymore. Side-by-side installation was supported during the migration period (April 2024 to July 2025) but classic Teams cannot connect to Microsoft 365 services as of July 2025. There is no value in having both installed.

Is new Teams the same as Teams for the web? No, but they share most of their underlying code. New Teams is a desktop wrapper around the same web-based Teams client that runs at teams.microsoft.com, but with platform integrations (notifications, file system access, OS-level presence) that the web version does not have. The shared code base is why most user-facing bugs affect both surfaces simultaneously.

Why does new Teams use less memory than classic? Classic Teams shipped its own Chromium runtime in every install; new Teams uses the WebView2 runtime that is shared with Microsoft Edge. The shared runtime means one engine instance serves multiple apps. Microsoft’s published benchmark of “50% less memory” reflects this; in practice, the savings vary based on what else on the system is using WebView2.

My organization blocked new Teams installation. What do I do? This is a tenant-level Group Policy or third-party endpoint management decision, often originating with the AllowAllTrustedApps registry block. End-user troubleshooting cannot resolve it — the IT administrator needs to update the policy. Microsoft published a fix for the most common form of this issue in KB5031455 / KB5031445 (October 2023 cumulative updates).

What about Teams on Mac? The Mac client follows the same retirement timeline. Classic Teams for Mac was retired in 2025; new Teams for Mac is the current supported version. The architectural change is similar — new Teams for Mac uses the macOS WebKit-based runtime rather than bundling Chromium.

Official references

Last updated: April 28, 2026.

↑ Back to top