526 error with Cloudfront Origin


Host registered as SSL For SaaS.
All origin registration information with K8S operates normally.
Strangely, only Origin registered with Cloudfront is spitting out 526 Error.
The settings except Cloudflare work perfectly, and the certificate is also an Amazone certificate.
The SSL setting is Full, so there is no problem, but I don’t know why 526 occurs.
When accessed via HTTP, Cloudfront normally redirects to HTTPS with 301.
Why does Error 526 occur in Cloudfront?

Please help me