In D7, when I upload a photo to a user profile page, the image displays if the original extension was a *.png file, but not if it was a *.jpg file. Uploading the files places them in sites/example.org/files/pictures, which indicates that the permissions are correct. But jpg files don't diplay on users' profile or forum posts. Instead the words "username picture" is displayed.
In admin/config/people/accounts, enable user pictures is enabled. However, I did not add a existing image field in admin/config/people/accounts/fields.
Basic page, articles and forum has an image field (field_image), with allowed extensions png, gif, jpg, jpeg.