Solution for Canon MP Navigator "Scan Failed" problem

When you try to use Canon MP Navigator to scan any documents or photo through Canon Multi-Function Printer, it said "Scan Failed" when pressing "Scan". A fix is provided as belows:

First identify "twain_32" folder on your system. Usually C:\Windows\twain_32

Under that folder, find the sub-folder name which match your printer's model (e.g. For MG6270, C:\Windows\twain_32\MG6270)

Edit Environment Variables and Add a New "System Variable" with variable name = Path

Press OK to finish. No reboot is required

Credit: dailytweak