External monitor not detected after security update

My external monitor (Dell U2715Hc) was connected to my 15" Macbook Pro (Late 2013) while I installed security update 2018-002 on MacOS Sierra (10.12.6). After restarting, my monitor is no longer being detected. The monitor was working before the restart, but not after. I didn't remove any cables. The monitor is connected by a displayport to mini-displayport cable.

I have tried:

Re-seating the displayport cable at both ends.
Switchting Thunderbolt ports on the Macbook Pro.
"Detect Displays" in the Display System Preferences.
Resetting the SMC

MacBook Pro, macOS Sierra (10.12.6)

Posted on Apr 4, 2018 10:34 AM

Top-ranking reply

ghammond100 Author

Level 1

4 points

Posted on Apr 4, 2018 2:45 PM

Fixed it. Disconnected everything, shut down, Reset SMC twice. Powered back on with nothing connected except power. Then connected display after booted up.

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External monitor not detected after security update

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