This error will be returned if the Dropbox API can't convert the requested image file to a thumbnail, such as if the file is too large, or doesn't contain valid image data. If the image isn't supported, there isn't a way to work around that to get the endpoint to return a thumbnail for that image.
We love to learn from the educators who use Dropbox. Whether you teach kids, teens, adults or a combination of all three, we want to know what apps and integrations you use with Dropbox to help with teaching. Which of the ones below is your favorite, or most used tool?