Error message, "hpPlugInInit.kext was installed improperly" I recently bought a MacBook Air and transferred my system information and user data via Migration Assistant. I used to get error messages on my old computer like this:


  The system extension “/System/Library/Extensions/hpPlugInInit.kext”
  was installed improperly and cannot be used. Please try reinstalling
  it, or contact the product’s vendor for an update


I hoped that this would go away with the new computer. (No, that's not why I bought it but it was supposed to be a good side-effect!)

But now I'm still getting this error message when installers are running. I don't have any HP printers, but I did at one time. How can I get this error message to stop? According to the HP support website there is an uninstaller I can run, but I don't have any such uninstaller.
Manually deleting hpPlugInInit.kext under /System/Library/Extensions/ gave me a solution.