ERR_SSL_PROTOCOL_ERROR

In short: The browser could not set up a secure (TLS) connection to the server.

In more detail: There was a problem negotiating the encryption.

In Depth

Possible causes

• Server supports only outdated protocols.
• Wrong configuration or certificate.
• Wrong time on the device.
• Antivirus or proxy interferes.

Solutions

1. Check date and time.
2. Update the browser, clear the cache.
3. Operators: check TLS configuration (TLS 1.2/1.3).

See also: HTTPS, TLS Record Protocol, NET::ERR_CERT_DATE_INVALID