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How to fix Sophos error 1721?

Do you see the “Sophos error code 1721” on your device screen while installing, upgrading, or uninstalling the Sophos Anti-Virus? Then make use of the instructions on this site to resolve the issue. Before getting into the solution for the problem, lets quickly understand the root cause of this issue. If the error code “Sophos error 1721” is displayed during the Sophos antivirus installation, the Sophos Endpoint Bootstrap log will display the information of the failed installation along with the error codes. Verify the installation logs in order to check which component has caused the error.

Sophos error 1721

The two main logs are:

  • Sophos Anti-Virus Major Install Log
  • Sophos Anti-Virus Major Custom Actions Log

The below-mentioned error may occur from the Sophos Anti-Virus logs: “Product: Sophos Error 1721. The Windows Installer package has encountered with a problem. The program that is mainly responsible to complete this install is currently unable to run.”


To troubleshoot the above-mentioned error message, check whether there is any missing service or component that is required for the installation and continue with the instructions on this site on how to clear the issue.

Steps to troubleshoot the error when some files are missing:

If the SAVONACCESSDRIV.INF, SOPHOSBOOTDRIVER.INF and/or NATIVE.EXE file(s) are/is missing, then the automated uninstallation will also fail, as these files are required for the uninstall process. It might also generate the error 0X80041f08 during the uninstallation, upgrading, or migration failure. This can be seen in the Sophos MSI log and the Windows Application Event log.

  • Go to “Regedit” on your Windows computer.
  • Go to the following location, “HKEY_LOCAL_MACHINE\Software\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall\”. Then click on the “Search” button.
  • Look for the Uninstall key of the Sophos Anti-Virus.
  • Go to another device that has the same version of Sophos Anti-Virus installed on it and then copy the folder, C:\Program Files (x86)\Sophos\Sophos Anti-Virus.
  • Paste the folder --- C:\Program Files (x86)\Sophos\Sophos Anti-Virus\ on the computer where you have the error. This will paste the following files.
  • Now, check whether the Sophos Anti-Virus software installs without any issues.

Steps to troubleshoot the error if files have been deleted manually:

If the install log suggests that few files related to Sophos have been deleted manually, then you have to add those files to the Sophos folder on your computer. Also, when you run the Process Monitor, you will see the following message: “msiexec.exe QueryOpen C:\Program Files\Sophos\Sophos Anti-Virus\Web Intelligence\swi_config.exe NAME NOT FOUND NT AUTHORITY\SYSTEM” Make use of these steps to resolve the Sophos error 1721 message:

  • Search for the file “swi_service.exe” or “swi_config.exe” from the SophosUpdate share. For example, you can find the file in the following location, \\SERVERNAME\SophosUpdate\CIDS\SXXX\SAVSCFXP\savxp\program files\Sophos\Sophos Anti-Virus\Web Intelligence (Substitute SERVERNAME for the server host name that has the SophosUpdate share).
  • Try to copy this file and then paste it into:
  • x86: C:\Program Files\Sophos\Sophos Anti-Virus\Web Intelligence
  • x64: C:\Program Files (x86)\Sophos\Sophos Anti-Virus\Web Intelligence (If the folder does not exist, create it and then paste the file in.)
  • Run the uninstallation using Programs and Features or Add/Remove Programs.

Now, you could install, uninstall, or update the Sophos antivirus software on your computer without the error message “Sophos error code 1721.” If the error message “Sophos error 1721” still appears, click the Call button on this page to get in touch with our technical experts to fix the error.