The woes of a Mac migration
Updated: Jan 12, 2022
Update, January 2022:
Shortly after publishing this post the Mac failed to connect to the display. Through a friend who works at Apple I got to a person who maintains the Thunderbolt firmware on Macbooks, and apparently the problem was caused by a combination of two issues; the first issue being a physical breakage in the Thunderbolt cable affecting only half of the wires inside, and the second being that Intel-based Macs can still manage to negotiate a Thunderbolt connection with only half of the wires working, while Apple Silicon Macs cannot. The workaround, supposedly, is to bypass the broken cable and use an external Thunderbolt cable connected to the daisy-chain port at the back of the monitor. I will update the post again once I tried it.
Earlier this week I got my new Apple Silicon Macbook Pro. Yes, everything they say about it is true. It's quiet. It's cool. It's blazingly fast.
As is my habit for the past 10 years, I used Migration Assistant to switch from my previous Macbook Pro (late 2019 15") to the new one. There were a few quirks relating to my music software ecosystem, but in general the migration was pain-free.
Until I connected my external display.
For the past 10 years I've been using an Apple Thunderbolt Display 27" as my main display and dock. It's an amazing monitor. It's got 3 USB ports, Ethernet, and in the (long-gone) age of Magsafe / Magsafe 2 it could also charge your Macbook - ages before the now-common practice of USB-C charging. When I got my first USB-C Macbook, I had to buy a Thunderbolt 2 to Thunderbolt 3 adapter and an additional power supply, as the display's charging capabilities were no longer relevant. Since then, another 5 years and 2 Macbooks have passed.
When I connected the display via the aforementioned adapter to my new Macbook, the display remained black. A USB device connected to the display blinked on and off. Nothing helped. I Googled the issue but no one seemed to have encountered the issue. I asked in FB groups. I called Apple support. No one had any idea what's wrong. People told me that it's a 10-year-old display and I should move on.
Finally, today, I got a tip from an Apple support engineer that I should try deleting the WindowServer.plist files. Specifically, these files:
/Library/Preferences/com.apple.windowserver.plist and ~/Library/Preferences/ByHost/com.apple.windowserver*.plist
I deleted these files, restarted the machine and a-voila - the display works! I lost some settings pertaining to display arrangement (to be expected) and to keyboard shortcuts (less expected) but generally everything seems to work now.
I'm writing this post mainly so that the next poor soul who encounters this issue and Googles it can solve it quickly.
You're welcome :)