Error during upgrade: "The error is: System.IO.IOException: The process cannot access the file (4276342)

The following errors may be shown during an upgrade:

Error unzipping file AfterMail EmailObjects.dll.
The error is: System.IO.IOException: The process cannot access the file 'C:\Program Files\Quest Software\ArchiveManager\AfterMail EmailObjects.dll' because it is being used by another process.
   at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
   at System.IO.File.InternalCopy(String sourceFileName, String destFileName, Boolean overwrite)
   at AfterMail.Installer.RemoteInstallerService.ZipUtilities.InstallZip().

Error decompressing install files: System.IO.IOException: The process cannot access the file 'C:\Program Files\Quest Software\ArchiveManager\AfterMail EmailObjects.dll' because it is being used by another process.
   at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
   at System.IO.File.InternalCopy(String sourceFileName, String destFileName, Boolean overwrite)
   at AfterMail.Installer.RemoteInstallerService.ZipUtilities.InstallZip()