Cause
The destination URL does not meet the rules: HTTPS, no credentials, no fragment or literal IP addresses, allowed port, up to 2048 characters.
What to do
Use a public HTTPS URL with a host name.
application/problem+json
{
"type": "https://masnet.com/developers/errors/invalid_url",
"title": "Invalid URL",
"status": 400,
"detail": "...",
"code": "invalid_url",
"correlation_id": "..."
}