Guest additions service fails to start--Windows 10 guest

[Arnie]

I just installed Windows 10 technical preview as a VB guest on Windows 7 host. Previously upgraded to most current VB v4.3.20 r96997. Install went fine and Win 10 appears to work. Installed guest additions, but seamless video mode does not work (can't get fullscreen). Shared clipboard/folder also doesn't work.

I uninstalled and reinstalled guest additions (most current version from Nov 2014) to no effect. The Guest Additions service in the guest is installed, but not running. When I attempt to start manually I get an error 'The service did not respond to the start or control request in a timely fashion.'

I have been running Win 8.1 as a guest for quite a while with no issues (guest additions or otherwise). I realize Win 10 preview is new; anyone else seeing this issue? Please advise if further details are needed.

[Kynolin]

I have the same error on a Windows 8.1 64 bit host and Windows 10 64 bit guest. I've tried installing the guest additions in compatibility mode as well with no luck. I'm running the latest version of VirtualBox, version 4.3.20 r96997.

[mpack]

You need the 4.3.21 GAs. They are the first to be tweaked for Win10.

[loukingjr]

The 4.3.21 GAs do not appear to work with the latest W10 (9926). Not for me anyway.

[Arnie]

Yeah, the 4.3.21 GAs do not work for me either on Win 10 build 9926 (host is Win 7 64-bit). Looks like I need to chill for a while until needed GA tweaks are made. Would appreciate feedback if anyone gets them to work. Thanks!

Also, based on moderator comments on other threads, the desired place to post about Win 10 GA is the Windows Guest board.

[mikeperu]

Guest additions services fails to start on Windows XP as well...

[loukingjr]

Guest additions services fails to start on Windows XP as well...

No idea what you mean. The guest additions have worked in Windows XP for years.