Weak key (RSA under 2048 bits)

What's going on

RSA keys shorter than 2048 bits are considered breakable and have been banned in public certificates since 2013. Modern clients refuse them.

How to fix it

Generate a new key (RSA 2048/3072 or EC P-256) and get a fresh certificate for it. The old key should be treated as compromised going forward — don't reuse it anywhere.

New to certificates? Start with the guide: How to read an SSL certificate.