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Hi All, I'm trying to execute through the steps found here: spin.atomicobject.com/2018/08/24/macbook-pro-external-monitor-display-problem/ The part that's tripping me up is copying a file to /Volumes/Macintosh HD/System/Library/Displays/Contents/Resources/Overrides/DisplayVendorID-10ac. In normal operating mode I get a "read only filesystem" error. I get the same error when booting up in recovery mode. I can use mount -uw to remount /Volumes/Macintosh HD in read-write mode, and I can copy the necessary file into the directory I need to, but when I reboot, the file is gone. How can I copy a file to /Volumes/Macintosh HD/System/Library/Displays/Contents/Resources/Overrides/DisplayVendorID-10ac and have it stick around permanently? Many thanks in advance for any help on this! Best, Brian Eriksen