OK this is weird.
Until before the Joomla 3.6.4 upgrade, I had a CB Paid Subscriptions cron task that ran with the following code in a cron.php file in my root, which worked fine for auto payments:
Code:
<?php
header("Location: http://mysite.co.uk/index.php?option=com_comprofiler&task=pluginclass&plugin=cbpaidsubscriptions&do=autopayments&key=d41d8cd98f00b204e9800998ecf8427e&format=raw");
return;
?>
After the Joomla upgrade this breaks the site with the message you saw earlier.
I now commented out the header line and the site loads fine...
Any ideas why that would be suddenly only on 3.6.4?
The exact debug error message was "Warning: Cannot modify header information - headers already sent by (output started at /home/......../public_html/plugins/system/contentstats/contentstats.php:38) in /home/......../public_html/cron.php on line 3"