We have a multi-site WordPress network at sb-agents.net with around 250 active subdomains. The latest version of Hustle (v126.96.36.199) seems to be having some conflicts with another plugin we have installed, SendGrid (v1.11.8). In the Changelog on the Hustle product page (https://premium.wpmudev.org/project/hustle/) it states that SendGrid was recently integrated into the plugin:
3.0.4 – 2018-07-09
– Add SendGrid and Zapier integrations.
If we have SendGrid installed and configured (https://wordpress.org/plugins/sendgrid-email-delivery-simplified/) and Hustle is also enabled, we get the following error:
mod_fcgid: stderr: PHP Fatal error: Cannot redeclare class SendGrid\Email in /var/www/vhosts/sb-agents.net/httpdocs/wp-content/plugins/wordpress-popup/vendor/sendgrid-php/lib/helpers/mail/Mail.php on line 933
This causes the webpage to return a 500 error.
For the time being, we have Hustle completely disabled on sb-agents.net. Please take a look at this for us and let us know if we can provide any additional information.