When trying to add a custom image I get “wrong number of arguments (given 0, expected 2…3)”?
I just did that prior to me reading about your issue. It worked for me (just for reference). FWIW, I grabbed the file from my desktop (in case the location of the file matters).
Figured out my problem. I was trying to load the ICO file instead of the JPEG file. Worked first try when I tried to upload the CORRECT file. My bad.