08-25-2019 11:01 AM - edited 08-25-2019 11:02 AM
I had the same problem, and finally found a solution. There is a free raw codec from Microsoft available now which works fine for my 6D MkII. It previews .cr2 files in Windows Explorer. You can find it here:
I found this helpful information here:
03-24-2020 11:03 AM
The 5D4 is singled out also. I bought mine last week (March 2020) and .CR2 files from that camera will not open. The .CR2 files from my 7D2 will. But that camera is 2 years old.