Save link fail, save image success

Hi, I have encountered a issue recently:
A folder doesn't have write permission for some special users, I accessed this redhat machine using this user, I opened Firefox, then saved link and saved image to this folder separately.
However, saving image succeeded, saving link failed.
I wonder if Redhat would do different operations while user save different content to the folder if user doesn't have write permission.
The error info is as blow.