What does ERR_SSL_PROTOCOL_ERROR mean?

Chrome tried to start an encrypted connection and the server answered with something that is not valid TLS. In almost every case the server is offering a protocol version or cipher the browser refuses, the certificate is broken, or something on the network is intercepting the handshake.

Device-specific

ERR_SSL_PROTOCOL_ERROR on Android

Why it happens on Android

Android devices with a wrong system clock, or an old WebView, reject otherwise valid certificates during the handshake.

The fix on Android

Set date and time to automatic, update Android System WebView from the Play Store, then clear Chrome's cache. Test the same URL on mobile data to rule out a captive-portal Wi-Fi network.

Is ERR_SSL_PROTOCOL_ERROR happening on your domain?

The SSL checker reads the live handshake: protocol versions offered, cipher suites, chain completeness and expiry. If it cannot complete the handshake either, the fault is server-side and not your browser.

Free, no signup. Runs from outside your network, which is the only way to tell a server fault from a local one.

If that didn't fix it

Android has its own failure mode, but ERR_SSL_PROTOCOL_ERROR has a wider set of causes that apply everywhere. The most common one overall is: the server only offers tls 1.0 or tls 1.1, which every current browser has disabled.

All causes and fixes for ERR_SSL_PROTOCOL_ERROR

ERR_SSL_PROTOCOL_ERROR on other platforms and devices

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Last verified: 16 October 2026 by the Lemwatch research team.