Insights from the QCecuring

Fix NET::ERR_CERT_COMMON_NAME_INVALID, SSL_ERROR_BAD_CERT_DOMAIN, and hostname mismatch errors. Covers SAN checking, wildcard rules, SNI issues, and certificate reissuance.

Fix the Java keystore error caused by wrong password, JKS/PKCS12 type mismatch, or corrupted keystore file. Includes recovery steps and keytool commands.

Fix the Java SAN validation error when connecting to servers with certificates that lack Subject Alternative Names. Covers certificate regeneration with SANs, OpenSSL commands, and keytool verification.

Fix the PKIX path building failed error in Java. Covers keytool import, cacerts configuration, corporate proxies, Spring Boot, Maven/Gradle builds, and Docker containers — without disabling certificate validation.

Fix the Windows revocation check error that blocks certificate validation, smart card logon, code signing, and HTTPS. Covers CRL distribution point issues, OCSP failures, and certutil diagnostics.

Fix the NET::ERR_CERT_AUTHORITY_INVALID Chrome error. Covers self-signed certs, missing intermediates, expired certificates, untrusted CAs, clock issues, and antivirus interference — with fixes for both visitors and site owners.

Fix the 'RPC server is unavailable' error in Active Directory Certificate Services. Covers certificate enrollment failures, CA unreachable, auto-enrollment broken — with certutil, firewall, and DNS fixes.

Fix the 'self signed certificate in certificate chain' error in OpenSSL, Node.js, curl, Git, and npm. Covers internal CA trust, corporate proxy CAs, and proper trust store configuration.

Fix the SSH 'Host key verification failed' error. Covers removing old keys, verifying new fingerprints, StrictHostKeyChecking options, and managing known_hosts at scale — with security warnings about MITM attacks.

Fix the SSH 'Permission denied (publickey)' error. Covers wrong key file, file permissions, SSH agent, authorized_keys issues, GitHub/GitLab, AWS EC2, and sshd_config — with ssh -vvv debugging.