Black Screen on Secondary

'Fine' on the actual monitor or, with it still plugged in, KVM works as well (no black screen)?

The monitor shows a normal desktop, but KVM is still black.

If the remote PC has more than one monitor

I would like you to update the video drivers for it and keep the monitor plugged in (if possible) until it is resolved.

Intel:
http://www.intel.com/p/en_US/support/detect?iid=dc_iduu

Nvidia:
http://www.nvidia.com/Download/index.aspx?lang=en-us

ATI \ AMD:
http://support.amd.com/us/gpudownload/Pages/index.aspx

Video drivers have been updated, but that doesn't appear to have solved the issue.

I rebooted the secondary, but when I connected via multiplicity I still got the black screen.  After logging in with RDP and connecting to the machine with multiplicity while RDP was still open, I would get to the login screen and multiplicity would work as expected.

After idling with multiplicity for a while, multiplicity gave me a message about having lost it's connection.  I could see what was happening on the secondary, but could not interact with anything.

Windows firewall is off on both machines, so I don't believe that is part of the issue.  Both machines are on the same subnet at the router, and there doesn't appear to be any issue that would prevent them from connecting at the router/switch level.  Ping works fine to the secondary when I'm getting the black screen issue and RDP works all the time as well.

If you are connecting via wireless, do you have more success if you changed the connection medium to Ethernet?

Connection is already via ethernet and rock solid via rdp. Only multiplicity has the problem.

When you are KVM connected, do you have this option available to you:

If so, and if you click it (and perhaps another Ctrl + Alt + Backspace), does it then show the login Window?

Also, all of your reports are of the ilk:

Is it the case that if the PC is not at a login screen that KVM works fine and consistently (without any prior use of RDP) - that the black screen issue is only seen when the PC appears to needed to be logged into?  In other words, if you knew the PC was logged into, and you used MP KVM, would it not have a black screen?

Ctrl-Alt-Backspace did not originally work, but switching the kvm to a different monitor and then doing a ctrl-alt-backspace did work to get me into the machine.  Not sure what's special about doing it that method, but it worked and the problem hasn't come back since.  I do know that the latest windows update reset a lot of settings for people, mostly around microphones, but other settings as well.  I'm wondering if something in that update also affected multiplicity.

As I posted in another thread, after the Windows 10 update 1803 my Secondary was also showing a blank screen (grey screen) when I went to access it. I could access it for a few minutes and then nothing. My fix was as simple going into the power options and disabling the option for the monitor turning off. I set mine to "Never" and it has worked every time since I changed it. I had it set on 5 minutes before the update with no problems. Don't know if this will help your situation because I didn't read anywhere that you could see the screen at all before the blank screen effect. Fingers crossed.

None of this helps me. I only have the built in monitor on my laptop. CTRL ALT Backspace does nothing.

On the laptop, the screen is normal, in KVM, grey screen.  CTRL Alt Delete does bring up the logout/shutdown options on the laptop, KVM still grey screen.

Drivers up to date.

Is your laptop one that has two graphics chips?

Yes, Neil. Intel 630  and nVidia 1050 Ti.

This issue, for this client, was resolved by forcing the PC to use a specific video card.

https://www.itechtics.com/use-specific-gpu/

https://www.addictivetips.com/windows-tips/force-app-to-use-dedicated-gpu-windows/

For clients that are connected to remote Secondary's that are headless (no monitor), that see this rare issue, these are the best \ cheapest solutions we are aware of:

https://www.amazon.com/s?k=hdmi+dummy+plug&crid=1YUHVFRCM5Y01&sprefix=hdmi+dum%2Caps%2C169&ref=nb_sb_ss_ts-doa-p_1_8

Sean Drohan
Stardock Support Manager

I am having the same issue. None of the above steps fixed the issue. Black screen on secondary monitor on KVM mode when a monitor is not plugged into the PC. Once I have a monitor hooked up directly to the secondary, it is visible on the primary.

Ctrl-Alt-Del and Ctrl-Alt-Backspace don't do anything. Video drivers are up-to-date. Connection to router is via Ethernet on both PCs. Monitor on secondary is set to never turn off. I tried 2 different dummy plugs and they did not work.

HDMI plugs or...?

DisplayPort plugs. The PC only has DisplayPort out.

Then I am uncertain if it would have the same effect - that Windows realizes they are there...

Sean Drohan
Stardock Support Manager

I just tried a DisplayPort to HDMI adapter with an HDMI dummy plug and that didn't work either. Any other ideas? May need a refund.

I gather you want the remote to remain headless?

Its not the adaptor type itself, it's how Windows sees it.  If I am not mistaken, HDMI connections are active where (generally), other connection types are passive.

This possibly may get around that:

https://www.amazon.com/Cable-Matters-DisplayPort-Supporting-Technology/dp/B00EDT0072

Sean Drohan
Stardock Support Manager

I purchased that item and it still does not work, unfortunately.

Should we force Multiplicity to use a gpu in particular? Or every aplication?

Can you add some context to the question - is something not working? What have you tried and failed with?

Sean Drohan
Stardock Product Lifecycle Manager

Oh, sorry.

I have the same problem as OP, a black screen on KVM but the secondary machine works fine. 
On Reply #13 you mention the issue was resolved by forcing the PC to use a specific video card.

On which PC? Do ia have to force KVM to use the video card? Or every app we want to use on the secondary machine?

Thanks for replying

Is the PC you are connecting to headless (no monitor) or does it have a monitor attached at connection time?

Also, is the remote PC 'awake'?  If not, for testing, make certain it is.

Sean Drohan
Stardock Product Lifecycle Manager

The PC i'm connecting to has a monitor. It is awake. Let's call it PC B

On my "controller" PC (PC A) When I open Multiplicity and select KVM and click Connect next to PC B, all I get is a black screen. 

When Multiplicity is my active window on PC A, I can control PC B with my keyboard (I can type and use shortcuts) but the screen is always black. My mouse is not working on PC B when Multiplicity is the active window on PC A