The file you have tried to upload is too big. Please make sure that your JPEG or PNG file is under 450 kilobytes.

Could the file size for uploading map images please be raised? I took a screenshot from a map camera and couldn't upload it because it's 485 kilobytes. This was just a regular steam screenshoot by pressing f12.

Something like one megabyte would be far more reasonable; and, allow for higher quality images to be uploaded.

You can re-size the image on your end to reduce the file size. It is very easy to meet the size limit and still have a high quality image.