Find the antivirus application and uninstall it from your computer.

To uninstall the application from Windows PC:

1. Open Control Panel. See the instructions on the Microsoft support website.
2. Go to Programs and Features.
3. Find the application in the list and click Uninstall/Change.
4. Follow the instructions of the Wizard.

To uninstall the application from Mac:

1. Open Finder and go to the Applications tab.
2. Find the application icon.
3. Drag-and-drop it to Trash.
4. Restart your Mac.

Try to install a Kaspersky Lab application once again.

If you have problems removing the application or the issue persists after successful uninstallation, use a tool for removing third-party software.

1. Write Kaspersky Rescue Disk to a CD/DVD or a USB drive. See this article for instructions.
2. Boot your computer from it.
3. Run a full scan of your computer. See this article for instructions. 

The the above recommendations did not help and Kaspersky Rescue Disk and Kaspersky Virus Removal Tool detected no threats, send a request to technical support with a detailed description of the issue: 

• Through My Kaspersky for Kaspersky Internet Security, Kaspersky Anti-Virus, Kaspersky Total Security, and Kaspersky Security Cloud. See the Online Help page for instructions.
• Through the Kaspersky Small Office Security Management Console for Kaspersky Small Office Security. See the Online Help page for instructions.

In your request, please provide the following:

• Registration data (date and place of purchase, customer name, activation code).
• Screenshot of the error message
• Kaspersky Get System Info tool report.

When switching to the new version of a Kaspersky Lab application, you may get the error "The application was not installed. Your computer may be infected by viruses." 

Should this error occur, remove the Kaspersky Lab application using the kavremover tool and reinstall it on your computer. See this article for instructions.

Kaspersky Lab applications use the Advanced Disinfection technology for eliminating active infections. This feature fights against malicious programs that are running on the computer and preventing anti-virus software from removing them.

If such malicious code is detected, the Advanced Disinfection technology does the following:

• Blocks the launch of any new processes in the system.
• Blocks any startup-related changes to the System Registry. 
• Blocks the creation of new files in startup folders.
• Blocks the creation of new executable files.
• Runs a scan of startup objects and removes the malicious code.
• Restarts the computer.
• Starts the system without the malicious code.

Upon restart, run a full virus scan, For a guide, click the link for your application: Kaspersky Internet Security, Kaspersky Anti-Virus, Kaspersky Total Security, Kaspersky Security Cloud or Kaspersky Small Office Security.

To enable the Advanced Disinfection technology:

1. Open the Settings window. To learn how to open the main application window, see this article.
2. Go to the Additional section and select Threats and Exclusions.

3. Select the checkbox Enable Advanced Disinfection technology.