Request error not JSON

Hi,

I’ve been trying to fix this for two days already.

Still nothing is working.

When I try to send a test email I get that error http://www.laciguena.com/wp-content/uploads/2016/04/Error-JSON-Mailpoet.jpg

Memory limit is at 256MB

The fix from that topic : https://ww.wp.xz.cn/support/topic/mailpoet-with-php-7-error/
is no longer valid.

I tried enabling debug mode and nothing related to that error showed up in the log.
I tried enabling the Mailpoet Debug and still nothing special showed up in the Queries.

I switched back to PHP 5.6 *(I was on PHP7) and I still have the exact same error.

I don’t know what is wrong here as this plugin is working on another website I own.

Is there some specific PHP Extensions required ?

I use woocommerce and I can’t really start disabling plugins…