If you are not able to upload an image file it may be that you are trying to upload a file that is not an accepted web friendly type of file.
The only type of image files that can be uploaded and will render well are those formats that end in jpeg (or jpg), tiff, or png.
A PDF is not an image file
A .pdf is not an image file but a portable document file (pdf). You can make a hyperlink to a .pdf file that will open to view it, but you can not upload a .pdf as an image.
To convert a .pdf to an image file, you should be able to open and view the file and export it as a .jpeg, .tiff or .png file. You can also take a screenshot of the open document and that should be a .png image file.
Other troubleshooting with uploading photos:
Raw photos: If you are using an app that takes raw photos, you will have to convert them to an image file before uploading.
Mega size photos: If you are using a device or camera that is set to take very large image files (I would say anything greater than 10MB) you will have trouble uploading it. Taking photos at that setting or higher are really for high quality printing. Today, a digital file really does not need to be larger than 3MB to be a high quality image for the web. Most devices are set to take photos at or around 3MB.
Reasons an image may not upload:
The image is not a .jpeg, .jpg, .tiff, .png, or file.
The file is too large for the wifi or cellular internet connection you are using. With a strong internet connection, a 3MB file should take only 1-2 seconds to upload. A 7-8MB file takes about 10 seconds.
The file is too large and will be very slow to upload. We do not recommend files larger than 20MB. Files that large are really intended for print media and not digital media.