@the_woodsman @wei2020 @bebops @DELL-Cares @Pouya85 

Didn’t @ my new post above. Not letting me paste a link, but it looks like this is a really old issue - I found a thread from 2014-2015 about the same problem with no resolution (the “solved” post was just someone saying they hadn’t found a solution).

I’m having the same problem with the XPS 13 9380 I bought in May 2019. I just bought an external monitor - it worked fine the first time I plugged it in, but since then has been causing my laptop to crash, either when I disconnect it, leave it connected overnight, or - just now - when I plug the HDMI cable (with USB C adaptor) in to the laptop in the first place. So now I can’t use my external monitor at all. So far a hard reset gets it up running again.

Any solution to this yet? 

Using an Amazon Basics high-speed HDMI cable and a Uni USB C to HDMI adaptor with a new Acer monitor, but from the other posts, it doesn’t sound like inexpensive hardware is the issue.

I just tried a solution 10 mins ago and it worked for me and for some others as well. Now I would be able to disconnect the external monitor and re-connect it without going black. I tried several times and it could work for now and hopefully working for ever. The solution is: 

Unplug the system, open the back cover,  disconnect the battery and hold the power button for 30 sec (to release any residual static charge). And then power up.  

or see the original post: 

https://www.dell.com/community/Laptops-General-Read-Only/XPS-13-black-screen/m-p/5123957#M919608

or see the Youtube video, which helped solve many other's black screen or not powering upproblem:

https://www.youtube.com/watch?v=NtyD2qlkaWY&t=22s

@DELL-Cares and @WhereIAm , I may have some insight into this issue. In sum, I think that it is a driver/software issue. I have a dual boot xps 13 9380 with Dell Windows 10 and Ubuntu Linux 18.04. When running Windows, plugging in my external monitor, a Lenovo Thinkvision m14, will randomly make the system unresponsive with a black screen. The only remedy is a 20s power button push. Echoing others, the system will often boot to a black screen when connected to an external monitor and be unresponsive, requiring another 20s power button push. When running Ubuntu Linux, the external display functions flawlessly when doing a restart or cold boot. Furthermore, the external display can be plugged in while the laptop is running without error

Another possible hint is that, while using Windows with an external display, the laptop will often fail to fully shutdown. The only clue to it not being fully off is a faint fan sound as well as a backlit keyboard. Often, another 10-20,s button push is required.

@the_woodsman , I am including you because you were the original OP. I've found some workarounds for myself that seem to work. I can get the XPS 13 9380 working with an external display quite consistently. I've found that the laptop will boot to Windows 10 with an external display. Generally, it will boot to a black screen on the first attempt around 60% of the time. When this happens, a 20 second power button press will shut the machine down. Upon powering it up again, the laptop will boot with both screens, this works more than 80% of the time. In a rarity, I will need to repeat this for a second boot cycle. I've never had to go beyond a second boot cycle, and I've used my external display at least 3 to 5 times (often more times) a week for several months. I've also found that unplugging/plugging it in is a no-go that will fail to a black screen at least 60% of the time. Furthermore, I've found that waking up the laptop from a sleep or screen-off event will fail to an unresponsive black screen around 80% of the time. In other words, don't try it. The workaround I've used is to turn off sleep and screen off events while plugged in via power management settings and put in a screensaver that only works while plugged in. These workarounds tend to work for me, as I never use a secondary display while the laptop is not plugged into power.

@Misalignment 

Thanks for the update. I've been chatting with several Dell tech support people who've offered many useless suggestions over the last few weeks. I'm not able to wait for a replacement system right now, so I've also resigned myself to a workaround.

I've been doing exactly the same thing as you since I started the original thread, and at least it allows me to still use the monitor without serious disruptions. I hope @DELL-Cares takes notice of this expanding thread and tries to find an actual solution to what seems like a pretty common issue.

@Misalignment I seemingly had this issue, searching for fixes I came across this thread. Anyway I logged a support ticket with Dell, who did two remote sessions which did the basics. Firmware upto date, etc. The ran "powercfg -h off" and then on...They also ran a Dell tool that applies know fixes. They made a Redistry change too.... But nothing did the trick.... However one thing that they did do, was to run and "sfc /scannow".

That came back and said that I had some corrupt files that could not be repaired. At this point they wanted to rebuild my Laptop so I did some further reseach off the back of the corrupt files. Example here....

2020-04-05 18:13:02, Info CSI 000034f8 Hashes for file member [l:13]'SBCModel.json' do not match.
Expected: {l:32 ml:4096 b:50ae0541f62e1300f751b474c9eca1402b09805b0000b7076fa8b38ab3d03bb9}.
Actual: {l:32 b:3220dc53bb415e664555d61f902ac3ddcfbc447331ab78c1585746578a74a020}.
2020-04-05 18:13:02, Info CSI 000034f9 [SR] Repairing corrupted file \??\C:\ProgramData\Microsoft\Windows\Models\\SBCModel.json from store

Searching for the above I came across this M$ article

https://answers.microsoft.com/en-us/windows/forum/all/microsoft-update-breaking-pcs-microsoft-reps/39715af1-33a1-43d0-918d-32e8f0be5587

I ran the commands from AndrewWay1's reply (takes ages to run),

enter Command Prompt as Administrator and run these:
dism.exe /online /cleanup-image /scanhealth
dism.exe /online /cleanup-image /restorehealth
dism.exe /online /cleanup-image /startcomponentcleanup

rebooted, ran the scan again (sfc /scannow) which then cam back clean.

Since then my laptop has, so far, come out of hibination and sleep successfully every time.

I am having a slightly different experience that might shed some light on the subject.

After much effort cleaning up drivers, I got my external Asus monitor to connect via USB-C to HDMI cable through a hub.  I have Windows 10 set as Extend these displays.  So far so good.  

When I power up my laptop, neither the external monitor nor the XPS13 screen comes on.  Both are powered but no display.

If I unplug the USB-C hub, the laptop screen comes on.  I can then plug in the hub and get the screen on the Asus monitor.  Not a huge hassle, but I don't understand why I need to disconnect the hub each time I power on.