VBoxClient: Could not find symbol address

Problem Description:

While one of my VirtualBox machines was running, a power crash happened and I had to restart my laptop.

After restarting the laptop, I started that virtual machine again, it started, but I got the following errors, and I was not able to access the machine from VirtualBox (seems to be hang), but I was able to access it from Putty:

VBoxClient: Could not find symbol address (x11Context.pXRRFreeMonitors)
VBoxClient: Could not find symbol address (x11Context.pXRRGetMonitors)

Two days before this issue, I upgraded the virtualbox , its extension pack and the VirtualBox additions on my Windows 10 laptop to 6.1.12-139181

After searching for solutions for couple of hours and trying many actions from similar issues, the problem is still there.

Sample actions that I tried but didn’t fix the problem:

I tried to kill and restart the vmsvga processes using the following commands:
ps -ef | grep vmsvga
/usr/bin/VBoxClient –vmsvga-x11

I tried to remove and re-install the same version of the Virtual Box additions from another terminal,but it didn’t fix the issue also.

I changed the Graphics Controller of this VM from VBoxVGA to VMSVGA , it didn’t help also.
I downgraded the VBox Additions from 6.1.12 to 6.1.10, but the problem still there.

Final Solution:

I downgraded the VBox Additions from 6.1.10 to 6.1.8, and this fixed the issue. Following are the steps:

You may download the virtualBox Additions 6.1.8 from the following location:
http://download.virtualbox.org/virtualbox/6.1.8/

Then you need to move this file to: C:\Program Files\Oracle\VirtualBox, and renamed as VBoxGuestAdditions.iso, replacing the existing one (e.g 6.1.12).

That is all.

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Thanks
Ahmed