This is the only KB that I can find that may help otherwise open a Support ticket to get further assistance - KB4259: Veeam Agent for Microsoft Windows can't be started or installed after upgrade to Windows 11

Great.  Glad to hear that was resolved.  Be sure to mark an answer to your issue to help others out. 

Hi,

Have you seen:

Likely the same issue.

This is great advice as I have seen this happen with the windows.old directory before on my own laptop.

You should be good with the advice above.

@Chris.Childerhose  Thank you for your help i resolve my problem with this 

https://forums.veeam.com/veeam-agent-for-windows-f33/can-t-install-veeam-agent-for-windows-5-0-1-on-windows-11-t78276.html

New-Item -Path 'HKLM:\SOFTWARE\Microsoft\Microsoft SQL Server\MSSQL11E.LOCALDB\MSSQLServer\Parameters' -Force

New-ItemProperty -Path 'HKLM:\SOFTWARE\Microsoft\Microsoft SQL Server\MSSQL11E.LOCALDB\MSSQLServer\Parameters' -Name 'SQLArg0' -Value "-T1800" -PropertyType String -Force

Hello @Franck, just like @MicoolPaul  has described above, there are certain steps to be able to install the Veeam Agent without running into this error as I have read in different forums on this issue. The following folders need to be deleted

• C:\Windows\System32\config\systemprofile\AppData\Local\Microsoft\Microsoft SQL Server Local DB\Instances”\VeeamEndPoint
• C:\ProgramData\Veeam\EndpointData

Access the following Registry path: HKEY_LOCAL_MACHINE\SOFTWARE\Veeam\Veeam Endpoint Backup 

• Create the following value under this key:
  Name = Recreatedatabase 
  Type = DWORD 
  Value = 1 
  Start Veeam Endpoint Backup service
  Allow some time for the new database instance to be created (5 minutes should be enough).

• Run regedit.exe and delete the Recreatedatabase value from HKEY_LOCAL_MACHINESOFTWAREVeeamVeeam Endpoint Backup key.
  Move VeeamBackup.mdf and VeeamBackup_log.ldf replacing the existing files in the target folder
  From:    C:Windows.oldwindowsSystem32configsystemprofile
  To:        C:WindowsSystem32configsystemprofile

Then restart your device and start the Veeam Endpoint Backup service.

Unfortunately it doesn't work for me

@Iams3le 

I might suggest that you remove the app completely and clean up any leftover files, then reboot and reinstall again.  I have the same Agent version running on my laptop with Windows 11 in the Beta channel so build 22593.1 and it is working without issue.

@Chris.Childerhose 

I deleted the app and all files about Veeam but after the new install the service doesn’t start 

Thank you very much @Franck for letting us know. Exactly same steps shared by @MicoolPaul. Thank you @Chris.Childerhose for your input as well. 

i have exectly this problem on windows 11 but how i can fix this? anyone have a step by step guide?

Just follow the articles noted in this thread as there has been great details given.

i am note sure how i can do this

Run the two PowerShell commands above noted to see if that fixes the issue for you.