Python urlretrieve image
I know it sounds dumb but, speaking of experience, check that the device on which the script is saving the files is not full (or have permission problems or whatever).
Modify your script to print out the URL instead of downloading the file. See if the URL is well printed and if there's no strange character that may be misinterpreted (including space).
If you are still in trouble, please post the script so we can have a look.
I'm downloading around 200 images from url's using urlretrieve.  They all download correctly except for one.  I have opened the url in my browser and the image loads correctly.  urlretrieve downloads something for that image but it doesn't open.  It gives me an error "The file xxx.jpg could not be opened." and it shows it's 1kb and no dimensions. When I manually save the image is shows as 289 kb and 1280x986.  Does anyone have any ideas what the problem might be?