Cause
The HTML contains elements or attributes that are not allowed (for example script, iframe or event handlers). The content is not echoed in the response.
What to do
Use only the supported grammar: paragraphs, level 2 to 4 headings, lists, quotes, code blocks, text, emphasis, code and HTTPS links.
application/problem+json
{
"type": "https://masnet.com/developers/errors/unsafe_html",
"title": "Unsupported HTML",
"status": 422,
"detail": "...",
"code": "unsafe_html",
"correlation_id": "..."
}