What is happening exactly then? Favicon does not save or maybe saving is fine but it does not appear in front-end? What is the link of your site and what is the path of the favicon that should be set?
when i migrated my website the favicon a tried to set worked... i don't know why i didn't try to change it again.so i would say that it's resolved by it self.
Comments
favicon can be changed under Theme options > Global > General section. All you need to do is replace existing favicon with the new one.