BUG REPORT WITH SUGGESTED FIX – Unexpected token <

Renzo,

I was hit with the “Unexpected token <” issue that seems to have been sporadically affecting many users of your plugin.

I have figured out the reason why it was only happening sometimes and for some people.

The actual json being returned was:

<br />
<b>Notice</b>:  Undefined index: logfileEnabled in <b>/var/sites/clientname.co.uk/public_html/wp-content/plugins/contact-form-7-mailchimp-extension/lib/functions.php</b> on line <b>260</b><br />
{"mailSent":true,"into":"#wpcf7-f278-p27-o2","captcha":null,"message":"Your message was sent successfully. Thanks."}

Digging into it, it seems that it happens when you have the show errors enabled with PHP and you have debug logging disabled with the plugin.

For me it was a simple fix to change the line from:

$logfileEnabled = $cf7_mch['logfileEnabled'];

To:

$logfileEnabled = isset($cf7_mch['logfileEnabled']) ? $cf7_mch['logfileEnabled'] : null;

After that the plugin submit worked for me.

Hopefully you can incorporate this into your next version 🙂

Looking at the code you might even be able to merge that with the line right after it but I just wanted to get a quick fix in there.

https://wordpress.org/plugins/contact-form-7-mailchimp-extension/