Been getting that irritating error (which shouldn’t exist in the first place if you ask me)? Here’s the quick fix:
Right click on the file you want. (No, we’re not going through the old way of 7-zip > Open archive technique.)
Choose ‘Open with…’
Select ‘Choose default program…’
Look for 7-Zip File Manager. If it’s not in the lists of recommended programs, search for it (click ‘Browse…’. Typically it’s under your C:\Program Files\7-Zip folder. Choose the 7zFM.exe program as default program.
Notice that 7-zip GUI is different from 7-zip File Manager. (Aha!)
Click ‘OK’ and try double-clicking your compressed files.