My external monitor recently stopped being recognised by my MacBook Pro (Early 2011 - 8,2, High Sierra, 10.13.6)

I have reset PRAM / SMC and tried a number of troubleshooting steps as outlined in the apple support docs. I've also tried Opt + Detect displays in the Displays preference panel.

I would like to watch a log file while I plug in the display (thunderbolt to DisplayPort) to see if I can track the issue down.

What should I be looking for either in the console app or by tailing and grep'ing an individual log file in terminal?

The monitor is an LG widescreen. There are no new display drivers. Around the same time, I've been having trouble installing the January security update but no idea if that is related.

The attached image shows a suspicious looking entry in the console.

enter image description here

  • 1
    Have you tried a known good cable? – IconDaemon Jan 31 '19 at 16:53
  • No. I only have 1 and it seems unlikely it would suddenly stop working. Its been fine for months / years – codecowboy Jan 31 '19 at 16:56
  • 1
    Cables can get bent, crunched between desk and wall, etc, and show no visible damage. In addition, if you frequently plug/unplug the MBP to take it with you, (it is a mobile device, after all,) the connector in the laptop can get wonky, too. Where I work, teachers plug into the projection systems in their classrooms sometimes multiple times a day. Those who do this most frequently have MDP/T-bolt ports that eventually 'go bad' in their MBAs. I suggest you get a second cable and give it a test. If it works, try the old cable again. If it fails, its the cable. – IconDaemon Jan 31 '19 at 17:02

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