Apple Remote Desktop constant resizing
20 Dec 2021
We use Apple Remote Desktop (ARD) for many things from working on headless servers to remote users working on Xsan connected systems while working from home. Occasionally, we run into a problem when connecting to a remove system via ARD where the window wildly resizes itself and eventually errors out. In some cases the cause seems to be a user changing the resolution of the display while connected remotely. Other times it has happened without a known cause but seems more common when the Mac has multiple displays.
The first thing to try is restarting the remote system. This has at least temporarily allowed us to connect several times. This also lets us see if the issue is restricted to a single user. Sometimes the solution was to remove the second display, but a recent problem led me to find what seems to be a better solution.
This user mentioned that they changed the resolution and then the problem started. After rebooting (or using ARD to log them out), connecting to the Mac at the Login Window worked as expected. This confirmed that the problem was restricted to the user’s home folder. After a bit of digging, the solution was to remove that user’s ~/Library/Preferences/ByHost/com.apple.windowserver.displays.<UUID>.plist. Each user can have their own settings for the display resolution so the file is in their home. Beyond that, a user used to be able to sync their home across multiple Macs, so the display settings are stored per system. That is what the ByHost folder is for and the UUID matches the systems Hardware UUID. Remove this file and then have the user try to connect again. The display resolution will be reset to default and they should be able to work.
If the resizing problem continues at the Login Window, then I would try removing /Library/Preferences/com.apple.windowserver.displays.plist. After that, it would be easiest to restart the Mac to have it reset the resolution to default.