If your virtual machine won't run after you update your VirtualBox and you get the error, “Result Code: E_FAIL (8x0004005),” it's most likely you just forgot to also update the extension plug-in. (Sometimes a VirtualBox update will automatically prompt for also installing the extensions, but in my experience it usually doesn't.) The version numbers of VirtualBox and the extension plug-in must match!
On the page where you download VirtualBox, be sure to also download the “Oracle VM VirtualBox Extension Pack.”
If you need to install an extension pack for an older version of VirtualBox because VirtualBox downloaded the second-latest release for you and you decide to stick with it for the time being, the download page should have a link to the pack you need.
- ⌃ On 2017 October 16 I was running VirtualBox v5.1.28 when v5.1.30 was released. At the time it wasn't convenient for me to update, so I ignored the update notice for a week and a half. Two days after October 16, v5.2.0 was released, but my installation of VirtualBox continued to ask me to download v.5.1.30. I didn't know about v5.2.0 until I went to get the extension pack for v.5.1.30.