virtualbox.org

I just downloaded and installed the latest release of VirtualBox for MacOS, 4.2.1. But when I attempted to install the extension pack from 4.2, it fails with the following error message. It looks like 4.2.1 may have been packaged with a back level release of a support library.

• Failed to install the Extension Pack /Users/X/Downloads/Oracle_VM_VirtualBox_Extension_Pack-4.2.0-80737.vbox-extpack.
  
  Failed to load the main module ('/Applications/VirtualBox.app/Contents/MacOS/ExtensionPacks/Oracle_VM_VirtualBox_Extension_Pack/darwin.amd64/VBoxPuelMain.dylib'): VERR_FILE_NOT_FOUND - dlopen(/Applications/VirtualBox.app/Contents/MacOS/ExtensionPacks/Oracle_VM_VirtualBox_Extension_Pack/darwin.amd64/VBoxPuelMain.dylib, 6): Library not loaded: /Applications/VirtualBox.app/Contents/MacOS/VBoxVMM.dylib
  
  Referenced from: /Applications/VirtualBox.app/Contents/MacOS/ExtensionPacks/Oracle_VM_VirtualBox_Extension_Pack/darwin.amd64/VBoxPuelMain.dylib
  
  Reason: Incompatible library version: VBoxPuelMain.dylib requires version 4.2.0 or later, but VBoxVMM.dylib provides version 4.1.23.
  
  Result Code: NS_ERROR_FAILURE (0x80004005)
  Component: ExtPackManager
  Interface: IExtPackManager {3295e6ce-b051-47b2-9514-2c588bfe7554}

Didn't I answer this question elsewhere? To me it looks like you are trying to install the ExtPack version 4.2.1 on a host where VirtualBox 4.1.23 is installed.