If some images are not displaying correctly, you must visit the image url directly to get the exact error message.
The image URL is not the same as the page URL; viewing the broken image icons on the parent page doesn't tell us anything useful.
How to open the image URL directly
- In Chrome, right-click on the broken image and choose "Open image in new tab"
- In Firefox, right-click and choose "View image"
- In IE, right-click the image and choose Properties. Copy and paste the Address (URL) field contents into the address bar of a new window.
Once you're viewing the image URL directly
If you do not get a specific error message, you must enable detailed error messages on your ASP.NET site.
If you have local access to the server, you can set the customErrors mode to RemoteOnly and access the URLs using 'localhost'.
Otherwise, you may need to temporarily set customErrors to Off, so you can get error messages from a remote location. Temporarily is the key word! Detailed error messages are considered a security risk and have enabled certain types of attacks to function. They should not be enabled for more than a few hours at most on a publicly accessible server.
You may also have to temporarily change <deployment retail to "false" for the customErrors setting to take effect.
The customErrors setting is case-sensitive; use "Off", "On", and "RemoteOnly".