Black Xorg loging screen after upgrade to VirtualBox 5.2.6 on Windows 10

[Frank Breitling]

After upgrading from 5.2.4 to 5.2.6 the graphical Xorg login screen remains black. I can still switch and login to a console, though. I am using XFCE on Debian Stretch testing with the corresponding guest additions.

After switching back to 5.2.4 login works as before.

First I thought it could be related to the following suspicious lines in /var/log/Xorg.0.log:

[ 6.766] (WW) Warning, couldn't open module vboxvideo [ 6.766] (II) UnloadModule: "vboxvideo"

However, vboxvideo module is there and these lines also appear in 5.2.4 and seem to be normal.

I am looking for a solution.

[Socratis]

Duplicate of #17463.

[Valery Ushakov]

#17463