Hello,
ive got the following error:

what have i done before:
Re-Installation Teams-wide-Installer via MSI an Parameters ALLUSERS=1
Repairing de Visual C++ 2012 / 2013 / 2015-2022
Re-Installation of Visual C++ 2012/2013/2015/ 2022
Delete te Reg Key HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\Teams\PreventInstallationFromMsi
Delete the UserProfil or the following folders:
del "%appdata%\Microsoft\teams\application cache\cache\*.*" /F /Q
del %appdata%\Microsoft\teams\blob_storage\*.* /F /Q
del %appdata%\Microsoft\teams\Cache\*.* /F /Q
del %appdata%\Microsoft\teams\databases\*.* /F /Q
del %appdata%\Microsoft\teams\GPUcache\*.* /F /Q
del %appdata%\Microsoft\teams\IndexedDB\*.db /F /Q
del "%appdata%\Microsoft\teams\Local Storage\*.*" /F /Q
del %appdata%\Microsoft\teams\tmp\*.* /F /Q
Nothing helps for solve the issue.. Every new User got this error an Teams doesn´t start.s...
The SquirrelSetup.log shows following entries:
2021-12-04 19:44:48> Program: Starting Squirrel Updater: --install . --checkInstall --source=default --silent --exeName=Teams.exe
2021-12-04 19:44:48> RegistryService: RegKeyExists: HKEY_CURRENT_USER\Software\Microsoft\Office\Teams has PreventInstallationFromMsi. Data - 1
2021-12-04 19:44:48> Program: Ignored request to install from Teams Installer (MSI) because PreventInstallationFromMsi was found and is set in registry
2021-12-04 19:55:45> Program: Starting Squirrel Updater: --install . --checkInstall --source=default --silent --exeName=Teams.exe
2021-12-04 19:55:45> RegistryService: RegKeyExists: HKEY_CURRENT_USER\Software\Microsoft\Office\Teams does not exist
2021-12-04 19:55:45> Program: Config already exists. Deleting first.
2021-12-04 19:55:45> Program: Starting install, writing to C:\Users\M.Mustermann\AppData\Local\SquirrelTemp
2021-12-04 19:55:45> Program: File does not contain contextual info: Teams.exe
2021-12-04 19:55:45> UpdateManager: using rootAppDirectory: C:\Users\M.Mustermann\AppData\Local\Microsoft\Teams
2021-12-04 19:55:45> Program: About to install to: C:\Users\M.Mustermann\AppData\Local\Microsoft\Teams
2021-12-04 19:55:45> Program: Setup.json exist, copying over
2021-12-04 19:55:45> RegistryService: RegKeyExists: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run has TeamsMachineInstaller. Data - C:\Program Files (x86)\Teams Installer\Teams.exe --checkInstall --source=default
2021-12-04 19:55:45> RegistryService: TrySetRegKey: HKEY_CURRENT_USER\Software\Microsoft\Office\Teams\InstallSource created
2021-12-04 19:55:45> RegistryService: TrySetRegKey: HKEY_CURRENT_USER\Software\Microsoft\Office\Teams\InstallSource set successfully as MSI
2021-12-04 19:55:45> CheckForUpdateImpl: Couldn't write out staging user ID, this user probably shouldn't get beta anything: System.IO.DirectoryNotFoundException: Could not find a part of the path 'C:\Users\M.Mustermann\AppData\Local\Microsoft\Teams\packages.betaId'.
at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)
at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, FileOptions options, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)
at System.IO.StreamWriter.CreateFile(String path, Boolean append, Boolean checkHost)
at System.IO.StreamWriter..ctor(String path, Boolean append, Encoding encoding, Int32 bufferSize, Boolean checkHost)
at System.IO.File.InternalWriteAllText(String path, String contents, Encoding encoding, Boolean checkHost)
at System.IO.File.WriteAllText(String path, String contents, Encoding encoding)
at Squirrel.UpdateManager.CheckForUpdateImpl.getOrCreateStagedUserId()
2021-12-04 19:55:45> CheckForUpdateImpl: Failed to load local releases, starting from scratch: System.IO.DirectoryNotFoundException: Could not find a part of the path 'C:\Users\M.Mustermann\AppData\Local\Microsoft\Teams\packages\RELEASES'.
at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)
at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share)
at Squirrel.Utility.LoadLocalReleases(String localReleaseFile)
at Squirrel.UpdateManager.CheckForUpdateImpl.<CheckForUpdate>d__3.MoveNext()
2021-12-04 19:55:45> CheckForUpdateImpl: Reading RELEASES file from C:\Users\M.Mustermann\AppData\Local\SquirrelTemp
2021-12-04 19:55:45> CheckForUpdateImpl: First run or local directory is corrupt, starting from scratch
2021-12-04 19:55:45> ApplyReleasesImpl: No delta packages found. Applying current release package.
2021-12-04 19:55:45> ApplyReleasesImpl: getting squirrel aware apps failed with exception Could not find a part of the path 'C:\Users\M.Mustermann\AppData\Local\Microsoft\Teams\current'.
2021-12-04 19:55:45> ApplyReleasesImpl: Writing files to app directory: C:\Users\M.Mustermann\AppData\Local\Microsoft\Teams\current
2021-12-04 19:55:51> ApplyReleasesImpl: Squirrel Enabled Apps: [C:\Users\M.Mustermann\AppData\Local\Microsoft\Teams\current\Teams.exe]
2021-12-04 19:56:07> ApplyReleasesImpl: Couldn't run Squirrel hook, continuing: C:\Users\M.Mustermann\AppData\Local\Microsoft\Teams\current\Teams.exe: System.OperationCanceledException: The operation was canceled.
at System.Threading.CancellationToken.ThrowOperationCanceledException()
at Squirrel.Utility.<>c__DisplayClass12_0.<InvokeProcessAsync>b__0()
at System.Threading.Tasks.Task.InnerInvoke()
at System.Threading.Tasks.Task.Execute()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Squirrel.Utility.<InvokeProcessAsync>d__12.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Squirrel.UpdateManager.ApplyReleasesImpl.<>c__DisplayClass30_1.<<invokePostInstall>b__2>d.MoveNext()
2021-12-04 19:56:07> ApplyReleasesImpl: About to RemoveOldShorcuts for Teams.exe, rootAppDir C:\Users\M.Mustermann\AppData\Local\Microsoft\Teams
2021-12-04 19:56:07> RegistryService: RegKeyExists: HKEY_CURRENT_USER\Software\Policies\Microsoft\Cloud\Office\16.0\Teams does not exist
2021-12-04 19:56:07> ApplyReleasesImpl: Registry value Software\Policies\Microsoft\Cloud\Office\16.0\Teams\PreventFirstLaunchAfterInstall does not exist
2021-12-04 19:56:07> RegistryService: RegKeyExists: HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\16.0\Teams does not exist
2021-12-04 19:56:07> ApplyReleasesImpl: Registry value Software\Policies\Microsoft\Office\16.0\Teams\PreventFirstLaunchAfterInstall does not exist
2021-12-04 19:56:07> RegistryService: RegKeyExists: HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Teams does not exist
2021-12-04 19:56:07> ApplyReleasesImpl: Registry value Software\Microsoft\Office\16.0\Teams\PreventFirstLaunchAfterInstall does not exist
2021-12-04 19:56:07> ApplyReleasesImpl: Registry flags are not set: proceed with default value NotConfigured
2021-12-04 19:56:07> ApplyReleasesImpl: Starting fixPinnedExecutables
2021-12-04 19:56:07> ApplyReleasesImpl: Examining Pin: File Explorer.lnk
2021-12-04 19:56:07> ApplyReleasesImpl: Examining Pin: Microsoft Edge.lnk
2021-12-04 19:56:07> ApplyReleasesImpl: Fixing up tray icons
2021-12-04 19:56:07> ApplyReleasesImpl: Couldn't rewrite shim RegKey, most likely no apps are shimmed: System.NullReferenceException: Object reference not set to an instance of an object.
at Squirrel.UpdateManager.ApplyReleasesImpl.<unshimOurselves>b__33_0(RegistryView view)
2021-12-04 19:56:07> ApplyReleasesImpl: Couldn't rewrite shim RegKey, most likely no apps are shimmed: System.NullReferenceException: Object reference not set to an instance of an object.
at Squirrel.UpdateManager.ApplyReleasesImpl.<unshimOurselves>b__33_0(RegistryView view)
2021-12-04 19:56:07> MeetingAddinInstaller: System.ArgumentException: Cannot delete a subkey tree because the subkey does not exist.
at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource)
at Microsoft.Win32.RegistryKey.DeleteSubKeyTree(String subkey, Boolean throwOnMissingSubKey)
at Microsoft.Win32.RegistryKey.DeleteSubKeyTree(String subkey)
at Squirrel.MeetingAddinInstaller.<InstallMeetingAddinAsync>d__15.MoveNext()
2021-12-04 19:56:07> MeetingAddinInstaller: StagedAppDirectory does not exist. Using Current
2021-12-04 19:56:07> MeetingAddinInstaller: There is no version.txt. Falling back to getting version from folder name
2021-12-04 19:56:07> MeetingAddinInstaller: Version: 1.0.21229.2; addinPackageDirectory: 1.0.21229.2
2021-12-04 19:56:07> MeetingAddinInstaller: .dead exists: False
2021-12-04 19:56:07> MeetingAddinInstaller: path to .dead: C:\Users\M.Mustermann\AppData\Local\Microsoft\TeamsMeetingAddin\1.0.21229.2.dead
2021-12-04 19:56:07> MeetingAddinInstaller: before cleanup unused versions
2021-12-04 19:56:08> MeetingAddinInstaller: Addin directory exists. Copy was successful
2021-12-04 19:56:08> MeetingAddinInstaller: Version 1.0.21229.2 of the meeting add-in is now installed
2021-12-04 19:56:08> PresenceAddinInstaller: Installing Teams Presence addin for Outlook...
2021-12-04 19:56:08> PresenceAddinInstaller: Copying C:\Users\M.Mustermann\AppData\Local\Microsoft\Teams\current\resources\assets\tlb\Uc.tlb to C:\Users\M.Mustermann\AppData\Local\Microsoft\TeamsPresenceAddin
2021-12-04 19:56:08> PresenceAddinInstaller: Copying C:\Users\M.Mustermann\AppData\Local\Microsoft\Teams\current\resources\assets\tlb\Uc.win32.tlb to C:\Users\M.Mustermann\AppData\Local\Microsoft\TeamsPresenceAddin
2021-12-04 19:56:08> PresenceAddinInstaller: check if UC TypeLib points to current\resources\assets\tlb\Uc.tlb
2021-12-04 19:56:08> PresenceAddinInstaller: Registering UC Typelib WIN32 under HKCU...
2021-12-04 19:56:08> PresenceAddinInstaller: UC Typelib WIN32 successfully registered to C:\Users\M.Mustermann\AppData\Local\Microsoft\TeamsPresenceAddin\Uc.win32.tlb under HKCU!
2021-12-04 19:56:08> PresenceAddinInstaller: Registering UC Typelib WIN64 under HKCU...
2021-12-04 19:56:08> PresenceAddinInstaller: UC Typelib WIN64 successfully registered to C:\Users\M.Mustermann\AppData\Local\Microsoft\TeamsPresenceAddin\Uc.tlb under HKCU!
2021-12-04 19:56:08> PresenceAddinInstaller: IM Provider registry key already exists!
2021-12-04 19:56:08> ApplyReleasesImpl: cleanDeadVersions: for original version of and current version of 1.4.00.31569
2021-12-04 19:56:08> ApplyReleasesImpl: cleanDeadVersions: exclude current folder stage
2021-12-04 19:56:10> RegistryService: TryDeleteRegKey: HKEY_CURRENT_USER\Software\Microsoft\Office\Teams\PreventInstallationFromMsi not found
What ca i do to fix the Access is denied.
Thx´s for any Suggestion and help
Marcus