Question: I am trying to make one form which give functionality like when user enter name and email,then PDF file starts download automatically.

And while i am applying this code in additional setting tab on submit button,it replay the error message like this.

I am currently working in local machine, i know error is in contact form 7 mail tab,but don't know how to fix it?

"There was an error trying to send your message. Please try again later."

Here is my contact form 7 code:

```
<label> Name
    [text* your-name] </label>

<label> Email 
    [email* your-email] </label>

[submit "Download Now"]

```

Here is code that i write in Additional Setting for download PDF file directly when form is submitted

```
on_sent_ok: "location = 'http://localhost/wordpress/wp-content/uploads/2017/08/pdf-sample.pdf';"

```

Answer: 
I Found solution for your need,just follow below stops,it can not send mail,but works fine in local machine as per your requirement.

1) Just paste below code in your Additional Setting tab in contact form 7

```
demo_mode : on

on_sent_ok: "location = 'http://localhost/wordpress/wp-content/uploads/2017/08/pdf-sample.pdf';"

```

2) Put below code in your .htacess file, after [/IfModule] and below # END WordPress

```
<FilesMatch "\.(?i:pdf)$">
   ForceType application/octet-stream
   Header set Content-Disposition attachment
</FilesMatch>

```
If someone is looking for an up-to-date answer since `in_sent_ok` is being deprecated, instead we can use: 

```html
   <script>
    document.addEventListener( 'wpcf7mailsent', function( event ) {
    location = 'http://example.com/';
    }, false );
    </script>
```