If you've connected your Facebook page to Promoboxx, but you see a "400", "402", "422", "500", or "502" (etc) error, you need to remove your "Business Integration" with Promoboxx, then reconnect your Facebook user/ Facebook page from scratch.
Go to facebook.com and log in to the Facebook user you use for Promoboxx. Once logged in, click the little arrow in the top-right corner, then click "Settings & Privacy", then "Settings":
Scroll down on the lefthand menu and click on "Business Integrations", check the box next to "Promoboxx", and click "Remove":
On the following popup, make sure you keep the boxes unchecked so existing Promoboxx posts will remain on your timeline, then click "Remove":
Return to the Business Integrations -> Social Accounts tab in your Promoboxx account, and reconnect your Facebook page. When you see the following popup , click "Choose what you allow" and turn on every toggle and check every box (very important) before clicking "Continue".
If you are still receiving an error, please email us at email@example.com