Had trouble with err_ssl_protocol_error on Chrome.

[Magnus Rosenqvist]

Had trouble with err_ssl_protocol_error on Chrome with a new setup for Remote Access VPN web login firepower(with fmc) and asa. But it worked fine on Firefox

It turns out that Chrome currently do not support Elliptical Curve Diffie-Hellman Group Group21 - 521-bit EC. Changing the ssl setting to Group20 - 384-bit EC fixed the issue.

Took me a long while to figure out. I hope someone else can save some time.

[irvinborder]

When a browser shows the Err_ssl_protocol_error, it indicates the browser is no longer able to access or initiate the secured communication. There is no definite guide for managing this error. Follow given steps to resolve this error from Client side:

• Try correcting the system date and time.
• Try clearing Google Chrome browsing data.
• Try clearing your SSL State.
• Try disabling the QUIC Protocol.
• Try checking your antivirus settings.
• Try enabling all SSL/TLS versions.
  
  Also, this error is because of the following aerver side problems:
• Invalid SSL or SSL is untrusted (self-signed)
• SSL Not installed properly
• Old Technology or SSL/TLS version for encryption