This has something to do with Stack Exchange's imgur upload interface. May be the file resize algorithm (ShadowWizard's comment below), file encoding settings, etc that goes while analyzing the image before the actual upload. I just uploaded the OP's suggested image by visiting to http://www.imgur.com and used "enter image URLs" option to upload the image.
Here is the direct link to uploaded image using "enter image URLs" at imgur:
![Direct link](https://i.sstatic.net/Fj4b2.jpg)
Here is the same above image added by uploading from URL using "SE's imgur interface":
Now, here is some food for thought. Upon doing further investigation on few things such as:
- Source site blocking imgur from accessing
- Imgur blocking/banning the source site
- Invalid image type
- URL format of the image without any special chars in it (especially in the "file name")
As far as the first three points goes, there is no issue at all. My first two screenshots voids all those first 3 points. So, the next thing left was to try and upload images from the same source with proper file name.
Here I am uploading http://www.litaniasports.com/images/stadium.jpg
using SE's imgur file uploader: (works perfectly!)
Now, I tried another image (from the same source) with a special char %20 i.e. a space in it http://www.litaniasports.com/facility/documents/830901%20Closed.jpg
and it throws the following error: (as said by OP)
Failed to upload image; the format is not supported
So, the problem is not about the file type or its format, it has something to do with the special char i.e. %20 (a space) in the image filename. The special character (%20) in the image filename has no issue when you do a direct web-upload (by entering image URL) on the imgur.com website. So, the issue seems to be on the SE's imgur interface where some kinda URL validation (and/or filename check) is happening before the image upload.
That's what I can think here. Please share your thoughts or any additional findings.
<error><message>Image format not supported, or image is corrupt.</message>...
; I'm checking something, though[email protected]
, and we can talk more - but I'm not going to dump the raw http (including keys, etc) here ;p