What is JotForm?
JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
At JotForm, we want to make sure that you’re getting the online form builder help that you need. Our friendly customer support team is available 24/7.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
Unfortunately you would not be able to alter the ALT field, but the issue is not with the ALT field, but with the default handling of the browsers when it comes to the upload file field.
To further explain the issue. This is not something related or limited to a jotform. It is happening on many file upload fields if the browser sees them as empty.
Now the reason why you see it like that on your jotform is because it is expecting another file to be uploaded and its entry is empty. This happens because our system creates a separate process in the background that starts with the upload - indicated with the fields with file meta under the box.
Basically this is expected to happen. If you however disable the multiple upload filed as soon as you select one file it will no longer show the message.