Error when installing VirtualBox Guest Additions on Windows 8.1 x64

[seyfin]

I am posing the full installation log including the error below

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Stopped logging into separate file Output folder: C:\Program Files\Oracle\VirtualBox Guest Additions Version: 4.3.20 (Rev 96996) No previous version of Oracle VM VirtualBox Guest Additions detected Detected OS: Windows 8_1 (64-bit) System Directory: C:\WINDOWS\system32 Checking for installation requirements for Vista / Windows 7 / Windows 8 ... Verifying file "C:\WINDOWS\system32\d3d9.dll" ... Verification of file "C:\WINDOWS\system32\d3d9.dll" successful (Vendor: Microsoft Corporation, Architecture: amd64) Verifying file "C:\WINDOWS\system32\dllcache\d3d9.dll" ... Skipping to file "C:\WINDOWS\system32\dllcache\d3d9.dll"; not found Verifying file "C:\WINDOWS\SysWOW64\d3d8.dll" ... Verification of file "C:\WINDOWS\SysWOW64\d3d8.dll" successful (Vendor: Microsoft Corporation, Architecture: x86) Verifying file "C:\WINDOWS\SysWOW64\d3d9.dll" ... Verification of file "C:\WINDOWS\SysWOW64\d3d9.dll" successful (Vendor: Microsoft Corporation, Architecture: x86) Verifying file "C:\WINDOWS\SysWOW64\dllcache\d3d8.dll" ... Skipping to file "C:\WINDOWS\SysWOW64\dllcache\d3d8.dll"; not found Verifying file "C:\WINDOWS\SysWOW64\dllcache\d3d9.dll" ... Skipping to file "C:\WINDOWS\SysWOW64\dllcache\d3d9.dll"; not found Output folder: C:\Program Files\Oracle\VirtualBox Guest Additions Extract: DIFxAPI.dll... 100% Extract: VBoxDrvInst.exe... 100% Extract: VBoxVideo.inf... 100% Extract: VBoxVideo.cat... 100% Extract: iexplore.ico... 100% Output folder: C:\Program Files\Oracle\VirtualBox Guest Additions Stopping VBoxService ... Stopping VBoxService via SCM ... Stopping VBoxService done Stopping VBoxTray ... Stopping VBoxTray done Output folder: C:\Program Files\Oracle\VirtualBox Guest Additions Extract: VBoxVideo.sys... 100% Extract: VBoxDisp.dll... 100% Extract: VBoxMouse.sys... 100% Extract: VBoxMouse.inf... 100% Extract: VBoxMouse.cat... 100% Extract: VBoxGuest.sys... 100% Extract: VBoxGuest.inf... 100% Extract: VBoxGuest.cat... 100% Extract: VBoxTray.exe... 100% Extract: VBoxControl.exe... 100% Extract: VBoxWHQLFake.exe... 100% Output folder: C:\WINDOWS\system32 Extract: VBoxService.exe... 100% Output folder: C:\Program Files\Oracle\VirtualBox Guest Additions Extract: VBoxVideoW8.cat... 100% Extract: VBoxVideoW8.sys... 100% Extract: VBoxVideoW8.inf... 100% Extract: VBoxDispD3D.dll... 100% Extract: VBoxOGLarrayspu.dll... 100% Extract: VBoxOGLcrutil.dll... 100% Extract: VBoxOGLerrorspu.dll... 100% Extract: VBoxOGLpackspu.dll... 100% Extract: VBoxOGLpassthroughspu.dll... 100% Extract: VBoxOGLfeedbackspu.dll... 100% Extract: VBoxOGL.dll... 100% Extract: VBoxD3D9wddm.dll... 100% Extract: wined3dwddm.dll... 100% Extract: VBoxDispD3D-x86.dll... 100% Extract: VBoxOGLarrayspu-x86.dll... 100% Extract: VBoxOGLcrutil-x86.dll... 100% Extract: VBoxOGLerrorspu-x86.dll... 100% Extract: VBoxOGLpackspu-x86.dll... 100% Extract: VBoxOGLpassthroughspu-x86.dll... 100% Extract: VBoxOGLfeedbackspu-x86.dll... 100% Extract: VBoxOGL-x86.dll... 100% Extract: VBoxD3D9wddm-x86.dll... 100% Extract: wined3dwddm-x86.dll... 100% Extract: C:\WINDOWS\system32\drivers\VBoxSF.sys... 100% Extract: C:\WINDOWS\system32\VBoxMRXNP.dll... 100% Extract: C:\WINDOWS\SysWOW64\VBoxMRXNP.dll... 100% Extract: C:\WINDOWS\system32\VBoxHook.dll... 100% Installing drivers ... Output folder: C:\Program Files\Oracle\VirtualBox Guest Additions Installing guest driver ... Executing: "C:\Program Files\Oracle\VirtualBox Guest Additions\VBoxDrvInst.exe" driver install "C:\Program Files\Oracle\VirtualBox Guest Additions\VBoxGuest.inf" "C:\Program Files\Oracle\VirtualBox Guest Additions\install_drivers.log" Installing driver ... INF-File: C:\Program Files\Oracle\VirtualBox Guest Additions\VBoxGuest.inf (1) ENTER: DriverPackageInstallW (1) Installing INF file 'C:\Program Files\Oracle\VirtualBox Guest Additions\VBoxGuest.inf' (Plug and Play). (1) Looking for Model Section [VBoxGuest.NTamd64]... (1) No matching devices found in INF "C:\WINDOWS\System32\DriverStore\FileRepository\vboxguest.inf_amd64_5dd6935fdf6c0fd0\vboxguest.inf" on the Machine. (1) No drivers installed. No devices found that match driver(s) contained in 'C:\WINDOWS\System32\DriverStore\FileRepository\vboxguest.inf_amd64_5dd6935fdf6c0fd0\vboxguest.inf'. (1) RETURN: DriverPackageInstallW (0xE000020B) ERROR (e000020b): Unknown error!

Execution returned exit code: 2 Error excuting ""C:\Program Files\Oracle\VirtualBox Guest Additions\VBoxDrvInst.exe" driver install "C:\Program Files\Oracle\VirtualBox Guest Additions\VBoxGuest.inf" "C:\Program Files\Oracle\VirtualBox Guest Additions\install_drivers.log"" (exit code: 2) -- aborting installation Error excuting ""C:\Program Files\Oracle\VirtualBox Guest Additions\VBoxDrvInst.exe" driver install "C:\Program Files\Oracle\VirtualBox Guest Additions\VBoxGuest.inf" "C:\Program Files\Oracle\VirtualBox Guest Additions\install_drivers.log"" (exit code: 2) -- aborting installation

[Frank Mehnert]

Looks to me like you try to install the VirtualBox Guest Additions on a Windows 8.1 host. Please reopen if I'm wrong. In that case please provide the VBox.log file for that VM session.