C++ Builder Indy error:1409442E:SSL routines:ssl3_read_bytes:tlsv1 alert protocol version

[BernardR 0]

Hi, I get the 1409442E error that seems to come back in various situations.

 

My Rad Studio version is 11 with update 1. The Indy version is 10.6.2.0.

 

I have tried TLS  1.0, 1.1 and 1.2 with no success.

 

This error happens with sites using CloudFlare that may be detecting inconsistencies in the request (I have tested with various headers and Mozilla "versions" too).

 

Any suggestions?

[Remy Lebeau 1256]

There is no way to diagnose this without seeing your actual code AND a log of the raw TLS handshakes that are producing the "protocol version" alerts.  Is it possible that the sites in question are requiring TLS 1.3?  Are other web browsers able to connect without error? Have you tried comparing their TLS handshakes to the ones Indy produces? Have you tried the WIP SSLIOHandler for OpenSSL 1.1x/3.0 yet, and does it produce the same errors?