I am using fileinput widget form krajee: http://plugins.krajee.com/file-input
What I am doing wrong using \'upload\' method ? When I upload files by pressing upload but
I was having the same issue, but I couldn't find a good solution, so I came up with a workaround.
I'm using the 'filebatchuploadcomplete' event, so I know when all the files in the batch are uploaded succesfully (even if there's only one file in the batch to be uploaded). When this event is triggered, I call 3 methods of the fileinput inside the closure function to clear, reset and re-enable the fileinput area (dropzone too, if you're using one).
THIS METHOD WORKS REGARDLESS IF THE ABOVE MENTIONED ERROR IS THROWN OR NOT BY THE PLUGIN.
Here's my sample:
$('#myFileuploadArea').fileinput({
//set the upload options here
...
...
...
}).on("filebatchselected", function(event) {
// trigger upload method immediately after files are selected
$('#myFileuploadArea').fileinput("upload");
}).on('filebatchuploadcomplete', function(event) {
// this part is triggered when all files are succefully
// uploaded from the batch, even if there was only one file selected
console.log('ALL FILES IN BATCH UPLOADED SUCCESSFULLY');
$('#myFileuploadArea').fileinput('refresh');
$('#myFileuploadArea').fileinput('reset');
$('#myFileuploadArea').fileinput('enable');
});