Occasionally, you may receive an email notification from Shopify with the subject "Your webhook is failing", containing the following message:
Your webhook for ... at https:// ... .postaffiliatepro.com/plugins/Shopify/shopify.php?ac=order&status=paid is failing to return a successful response.
This webhook has been attempted ... times. If your webhook continues to fail, it will be removed and your application will not receive any more notifications.
Despite these notifications might look alarming you do not need to worry and can ignore them. Such notifications are automatically sent every time when our data centers do not reply back to Shopify within 5 seconds with a successful "200 OK" response to the request, mostly due to a slight delay in the connection.
If there's no response sent within the given time, or an error is returned, Shopify retries the connection again 19 times over the next 48 hours. It is possible that we have already processed the request that correctly arrived to us after those 5 seconds on the first attempt, Shopify just doesn't consider that anymore. In that case, we would ignore (not change the status or don't refund the commission again) the same repeated delivered requests.
Only after those 20 tries over 48 hours will fail to receive a successful response, your Shopify webhook will be deleted, and you will receive a separate email notification with the subject "Your webhook has been removed":
Your webhook for ... at https:// ... .postaffiliatepro.com/plugins/Shopify/shopify.php?ac=order&status=paid has been removed on ... because it's failing to return a successful response.
When the issue is fixed, you'll need to re-create your webhook.