Form Tag Attribute for Uploading Files

If you build a form to upload a file, the form tag's attributes must include this:

enctype="multipart/form-data"

If it's not present, the form won't upload any files.

When the form is not used to upload files, the enctype attribute in the form tag is optional. If specified, the enctype attribute may have any of these values:

application/x-www-form-urlencoded
multipart/form-data
text/plain

If a form tag has no enctype attribute specified, application/x-www-form-urlencoded is default. But the default value won't work to upload files; it is the wrong value for that.

For reference, here is an example form tag.

<form method="post" enctype="multipart/form-data" action="form-submission.php">

(This blog post first appeared in Possibilities newsletter.)

Will Bontrager