Second Monitor stopped working after Sequoia 15.5 update

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Level 1

5 points

Second Monitor stopped working after Sequoia 15.5 update

I have been using a usbc dock station to connect two monitors to my macbook air. It was working flawlessly until today, when I installed the 15.5 update. I have followed every suggestion I could find: multiple resets, unplugging, replugging, removing the /Library/Preferences/com.apple.windowserver.displays.plist file, re-installing all the display drivers, etc. Please let me know what I can do. I really need to have two monitors for my work.

Thank you!

MacBook Air

Posted on Jun 3, 2025 11:09 AM

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Answer 1

Top-ranking reply

Luis Sequeira1

Level 9

73,008 points

Jul 16, 2025 2:59 AM in response to petterikivimaki

petterikivimaki wrote:

• I found a cure for that disease:

Open "System preferences"

• Open "External devices" (I am not sure since I use the finnish)

• Change "Allow the connection of external devices" to "Ask Always"

• Reboot

Works!

That's interesting. Would other settings like "Always Allow" not work as well?

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Answer 2

Jun 4, 2025 12:53 AM in response to siavosh273

siavosh273 wrote:

Thanks for your response.

Yes it does. It's been updated May 27th.

Using more than one external display in a MacBook Air is something that is going beyond what Apple says is supported, so it can break with any new system update.

I'd contact DisplayLink. Maybe a new update from them is needed.

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Answer 3

Jun 3, 2025 11:37 AM in response to siavosh273

Does this dock use DisplayLink software? Is it up to date?

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Answer 4

Jul 15, 2025 9:37 PM in response to jcontrini22

I found a cure for that disease:

Open "System preferences"
Open "External devices" (I am not sure since I use the finnish)
Change "Allow the connection of external devices" to "Ask Always"
Reboot

Works!

Reply

Answer 5

Jun 3, 2025 7:49 PM in response to siavosh273

I'm having the same issue! Tried everything and have been trying to figure this out for hours. Initially, only 1 of the 2 monitors wasn't working. Now, neither work. Continuously says "USB display device is not connected". I've been using macOS Instant View for years with no issue. Updated to 15.5, and it's been a disaster. Any help would be greatly appreciated.

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Answer 6

Jun 9, 2025 4:09 PM in response to siavosh273

I am having the same problem. I have a Mac Mini Apple M4 Pro with two ASUS 5K monitors (PA27JCV) that have been working great. The second monitor quit working after the last Sequoia update, 15.5. I tried many of the suggestions including changing cables, switching monitors, changing which ports on the Mac Mini I used and finally deleting the com.apple.windowserver.displays file. Since that did not solve the problem, I put it back. Looking for any additional ideas. Also, I am not using any devices that require the DisplayLink app. I did download it but it did nothing since none of my devices call for it.

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