Originally Posted by AaronP
The driver changed from using read() to using mmap() on the specified CustomEDID file, and apparently that fails for the special files in /proc, which is arguably a kernel bug. Please try copying the contents of /proc/acpi/video/IGPU/LCD0/EDID to a normal file on the filesystem and then pointing CustomEDID at that.
Both myself and 65kid have always been using files dumped from Windows. And rather than breaking user configurations, why not revert that change?