SSL Errors

NET::ERR_CERT_WEAK_SIGNATURE_ALGORITHM means the browser rejected the website certificate because it was signed with a cryptographic algorithm that is no longer considered secure. In practice, this usually points to legacy certificates that still rely on SHA-1 or similarly outdated signing methods that modern browsers distrust. :contentReference[oaicite:0]{index=0} This is not a cosmetic warning. It is a certificate … Read more

HSTS error usually appears when a browser is forced to use HTTPS for a website, but the site’s certificate or secure connection is broken. HSTS stands for HTTP Strict Transport Security, a policy that tells browsers to connect to the site only over HTTPS and not allow fallback to HTTP. :contentReference[oaicite:0]{index=0} This is why HSTS … Read more

SEC_ERROR_UNKNOWN_ISSUER means Firefox does not trust the certificate issuer presented by the website. In plain language, Firefox cannot build a trusted certificate chain from the website certificate back to a known, trusted root certificate, so it blocks the connection as a security risk. :contentReference[oaicite:0]{index=0} This error is common on sites with broken certificate chains, self-signed … Read more

PR_END_OF_FILE_ERROR is a Firefox-specific secure connection error. It usually appears when Firefox cannot complete the HTTPS connection because something on the path interrupts or breaks the TLS handshake before a trusted secure session is established. :contentReference[oaicite:0]{index=0} This error is common on sites that otherwise work in Chrome or Edge, which makes it confusing. In real … Read more

ERR_SSL_KEY_USAGE_INCOMPATIBLE means the browser received a certificate whose key usage settings do not fit the way that certificate is being used for HTTPS. In most cases, the certificate is real and the hostname may even be correct, but the certificate extensions are wrong for modern TLS. This error is especially common on internal websites, self-signed … Read more

SSL_ERROR_BAD_CERT_DOMAIN means the website is presenting an SSL certificate that does not match the domain name you opened. In practice, the browser asked for one hostname, but the server responded with a certificate issued for a different one. This error is common on misconfigured subdomains, wrong www redirects, multi-site servers, reverse proxies, and Cloudflare setups … Read more

NET::ERR_CERT_DATE_INVALID means the browser thinks the website’s SSL certificate is outside its valid date range. In plain English, the certificate looks expired, not yet valid, or the device checking it has the wrong date, time, or time zone. This error is common in Chrome, but the same root problem can appear in Firefox, Edge, Android, … Read more

Your Connection Is Not Private means the browser cannot trust the website’s HTTPS certificate or the secure connection in front of it. Sometimes the problem is on the website. Sometimes it is on your device, network, antivirus, VPN, or proxy. This guide shows how to fix Your Connection Is Not Private quickly, whether you are … Read more

ERR_CERT_COMMON_NAME_INVALID means the SSL certificate presented by the website does not match the hostname in the browser address bar. In simple terms, the browser asked for one domain, but the server replied with a certificate for a different name. This error is common on new domains, misconfigured subdomains, reverse proxy setups, Cloudflare zones, and servers … Read more

ERR_SSL_VERSION_OR_CIPHER_MISMATCH means the browser could not negotiate a secure HTTPS connection with the website. In most real cases, the cause is not random. It is usually a broken TLS setup, an invalid certificate assignment, an unsupported protocol version, or a mismatch between the server, CDN, and browser. This guide explains how to fix ERR_SSL_VERSION_OR_CIPHER_MISMATCH from … Read more