Uploading file Angular.js FormData

I got it.

I was using express.multipart in the server side with defer option "express.multipart({defer: true})"

Because of that, sometimes the execution reached the code where I manage the post request to get the image with "req.files.file" before form's "end" event in express.multipart module is fired where the module sets req.files:

form.on('end', function(){ if (done) return; try { req.body = qs.parse(data); **req.files = qs.parse(files);** if (!options.defer) next(); } catch (err) { form.emit('error', err); } });

So sometimes req.files.file = undefined, simply because is not set yet...

Getting rid of {defer: true} option solves my problem. Nothing to do with one or another image.

Here you are the doc of "defers" option in express.multipart module:

"defers processing and exposes the Formidable form object as req.form. * next() is called without waiting for the form's "end" event. * This option is useful if you need to bind to the "progress" event, for example."