54051: Invalid webhook URL

The specified 'WebhookUrl' parameter is not a valid URL or exceeds the allowed length of 512 characters.

• You did not pass a correctly-formatted URL.
• You are crafting HTTP requests yourself and passed a URL, but did not percent-encoded it.
• You passed a webhook URL that is longer than 512 characters.

Confirm that you are providing a fully-qualified, percent-encoded HTTP URL that is no longer than 512 characters.