The "Accept" rule in the latest version of jQuery Validate now expects a mime type to be specified, not a file extension.
A new "Extensions" rule has subsequently been added for this purpose.
Note that as of v1.90 both of the above rules are now available separately inside the "Additional Methods" download.
Comments: The solution: 1. FileExtensions attribute will evaluate to the 'extension' method of JQuery Validation, and Accept attribute will evaluate to the 'accept' method 2. If the 'extension' method is not present (using MVC5 with an older version of jquery validation) then the FileExtensions attribute would use the 'accept' method, and Accept attribute will be ignored on the client side altogether. Fixed in https://aspnetwebstack.codeplex.com/SourceControl/changeset/803b6de9af1b4e77f805071bd9e521687903681b
A new "Extensions" rule has subsequently been added for this purpose.
Note that as of v1.90 both of the above rules are now available separately inside the "Additional Methods" download.
Comments: The solution: 1. FileExtensions attribute will evaluate to the 'extension' method of JQuery Validation, and Accept attribute will evaluate to the 'accept' method 2. If the 'extension' method is not present (using MVC5 with an older version of jquery validation) then the FileExtensions attribute would use the 'accept' method, and Accept attribute will be ignored on the client side altogether. Fixed in https://aspnetwebstack.codeplex.com/SourceControl/changeset/803b6de9af1b4e77f805071bd9e521687903681b