You receive an "Setup believes VSAPI based antivirus product is installed already" error message when you try to install Antigen in VSAPI mode, and the installation fails (905988)


The information in this article applies to:

  • Sybari Antigen 8.0 for Microsoft Exchange
  • Sybari Antigen 7.5 for Microsoft Exchange
Important This article contains information about how to modify the registry. Make sure to back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to back up, restore, and modify the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows registry

SYMPTOMS

When you try to install Antigen in Virus Scanning API (VSAPI) mode, you receive the following error message:
Setup believes VSAPI based antivirus product is installed already. Antigen can't co-exist with any VSAPI based antivirus product.
After you receive this error message, the installation fails.

CAUSE

This issue may occur if you previously used VSAPI to install other antivirus software. When you use VSAPI to install antivirus software, the following registry subkey is created to save information about the VSAPI library:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeIS\VirusScan

If this registry subkey is present in the registry when you try to install Antigen in either Extensible Storage Engine (ESE) mode or in VSAPI mode, the installation fails.

RESOLUTION

Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.
To resolve this issue, follow these steps:
  1. Click Start, click Run, type regedit, and then click OK.
  2. Locate and then click the following registry subkey:

    HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeIS\VirusScan

  3. Right-click the VirusScan registry entry, and then click Delete.
  4. Quit Registry Editor.

MORE INFORMATION

If you install Antigen in VSAPI mode, you cannot run multiple anitvirus software solutions at the same time.
Modification Type:MajorLast Reviewed:11/4/2005
Keywords:kbtshoot KB905988
©2004 Microsoft Corporation. All rights reserved.