After update from 10.15.3 to 10.15.4 external displays doesn't work via docking station

Also happening to me. MacBook Pro (16in, 2019) and CableMatters external USB-C adapter with dual HDMI input. Computer crashed twice upon restart after upgrade.and trying to connect the external monitors. Now loads but doesn't recognize the monitor as being connected at all.

I have the same problem, today I decided to make a clean install of macos 10.15.4 and my two external displays connected to a dock dell D6000 don’t work. The main display start blinking while it’s connected to the dock and the external displays don’t show anything.

I tried the latest drivers from displaylink but it didn’t work... Maybe a fast solution is to make a downgrade to the 10.15.3

Same issue here.

I use TOTU docking station bought from Amazon.

The USB-C cable connected to my 2019 MacBook Pro "13 no longer output signals to my two external monitors, and it no longer charges my MacBook either.

However, the very same USB-C cable connected to the same TOTU docking station can still charge my other USB-C devices, so I'd think that Apple added something in the new MacOS 10.15.4 to block 3rd party charger. Since that's very same USB-C cable connecting to my docking station, my external monitor will not get the signals from my MacBook either. Just my 2-cent.

Similar issue here. User with a 2010 Apple Cinema display, which involves three connectors: USBc for power, USB a>c adapter for a/v, and a UPTab USB-C Type C to Mini DisplayPort Adapter. As the user stated, it's not pretty, but it worked up until the 10.15.4 update.

I'm having the same problem after upgrading to 10.15.4. External display no longer works either directly from Thunderbolt-Displayport or through a CalDigit T3+ dock running firmware version 44.1). I can still use the external display via HDMI, but am stuck at 30 Hz.

Catalina 10.15.3 did not have this problem, and indeed connecting another MBP that hasn't been upgraded works fine.

Resetting SMC and PRAM don't seem to matter.

@apple Please fix. The timing on this is terrible.

I can't use my Lenovo Thunderbolt 3 gen 2 dock after the upgrade to 10.15.4 Prior to the upgrade it worked without the need for any drivers. I've tried to install the latest one ( v 5.2.1)from DisplayLink, as well as the beta driver (r 0.5) but nothing happens. I also followed the procedure about setting the screen recording permission in the system Preferences, but nothing works... must be an error in the 10.15.4 code. Hope Apple fixes it ASAP

I am also a user of a 2010 27" Apple Cinema Display (DisplayPort) combined with a (2020) 16" MacBook Pro, and until updating to macOS 10.15.4 I could use the ALOGIC "USB-C 8-in-1 Dock" to connect my Cinema Display (and connected USB peripherals) to my MacBook Pro with a single cable going into the MacBook Pro. Admittedly, sometimes it was necessary to disconnect/reconnect the DisplayPort from the "dock", but it has always worked after a max. of 3 disconnect/reconnect cycles. Now, no image...

Apple this is getting out of hand. In addition to this display issue I’ve had 4 crashes. Each time I close the lid of my MacBook and open it, it has “restarted because of an error”

I am really frustrated with loosing my work. I have a brand new 16 inch MacBook. Your silence so far is really telling....

After updating to 10.15.4, my external monitor Dell UP2414Q which uses Display Port 1.2 stopped working. I don't use a docking station, but my issue must be a relevant problem. When I dropped the connection to 1.1a in the menu, the OS is able to display the screen at 4k@30hz. Prior to this version, in 10.15.3, the monitor worked just fine.

There is a post in the displayLink forum where they give a solution for the DELL D6000 Docking station (https://www.displaylink.org/forum/showthread.php?t=66996&page=4) which is to update the firmware of the Dock.

Before update the Dock I made a SMC reset as many users advice which fixed the problem of the laptop don't charging from the dock, now my MBP is working with my two monitors without any problem. I hope this can be useful for someone else.

reset of SMC is a temporary fix. The same behaviour returned after a few minutes. After start of the screensaver, the external monitor turns off and never wakes up again. Disconnecting the external monitor wakes up the internal display. Reconnecting the external monitor too the MBP starts process of connecting of the external display, the screen turns itself off (like starting to build an extended display) but never gets to the point of actually displaying anything. The internal display stays off and the external monitor stays dark or starts to wake-up and turn off, wake-up turn off repeat.

I am no apple software expert, but its like the system detects the external monitor, starts or changes a driver setting but the driver crashes while setting up the new monitor. The system detects the crash, initialises the video driver, gets a signal that an external monitor is connected and voila, the cycle repeats.

I am "glad" others are having the same issue. I thought I was loosing my mind! This started immediately after the 10.15.4 update. I am using an HP USB-C Dock G5 and the external monitor connection is very unpredictable. The dock supports DisplayPort and HDMI and neither will wake the monitor reliably. If I plug and unplug 2-3x it may eventually work. All other devices connect work. Sometimes the MBP acts like the monitor is connected but the display is black. Other times it acts like the monitor was never connected.

I have tried PRAM and SMC resets to no avail. I have a 16" MBP. I really hope Apple is looking into this.

same with landingzone docking station unless laptop is open. I have 2 x 4k screens with macbook pro 15 2018. since 10.15.4 laptop screen has to be open, but when laptop is open my 4k screens drop to 2k. Apple you need to fix this.

My entire organization has had this issue with all of our MacBook Pros after upgrading to Catalina 10.15.4. FIX THIS GARBAGE APPLE! This has been going on for months! External monitors were working fine 10.15.3 then suddenly NOTHING! The system preferences no longer give the display option to detect external displays. Is this yet another money grubbing gimmick? Are you going to tell us that we have to buy Apple display cables, or some other crap. We are all probably going back to PC's of this issue isn't resolved soon. None of the suggester "fixes" for this issue work. Get you $hIt together Apple.

Non compliant hubs may use work arounds that get broken when software is upgraded.

Why would some work and some not?

Look at hub support pages. Why are some experiencing problems and others not? Just saying...