Campo de carga de archivos: recibo un error al cargar un archivo

tengo problemas con el envío de mis formularios, urgente 

Hi ecis,

Our Spanish Support agents are busy helping other Jotform users right now, so I'll try to help you in English using Google Translate, but you can reply in whichever language you feel comfortable using. Or, if you'd rather have support in Spanish, let us know and we can have them do that. But, it might take a while until they're available again.

Now, coming back to your question, I cloned your form and tested it to see if I could replicate the issue, but everything was working properly. I was able to successfully upload a file and submit the form. Check out the screencast below to see my results:

There is a possibility that the file you're trying to upload is broken, non-existent, or has a different file format. Can you try uploading a different .jpg file, or any other file with an accepted format (i.e., .pdf, .doc, .docx, .xls, .xlsx, .csv, .txt, .rtf, .html, .zip, .mp3, .wma, .mpg, .flv, .avi, .jpg, .jpeg, .png, .gif), and see how it goes? Before you do, clear your browser's cache and cookies first. You can also use Incognito or a different browser for this. If you're still going to use a mobile browser or the Jotform Mobile app, close and reopen it, and then test the form again. I've cleared your Form Caches to refresh the data. If the same thing happens again, we'll investigate it more to see if we can figure out what's going on.

Give it a try and let us know how it goes.