The following patch disabled the TLSv1.2 protocol for MariaDB Connector/C when using Schannel:
With this change, if you set ssl_cipher to a TLSv1.2 cipher (e.g. AES256-GCM-SHA384) and if you try to connect to a server that supports TLSv1.2, then the connection will fail with an error like:
This even happens if you set ssl_cipher to a TLSv1.2 cipher that also supports TLSv1.1 and TLSv1.0 (e.g. AES256-SHA).
However, for some reason, setting ssl_cipher to "TLSv1.2" allows the connection to succeed without any errors. I see that this string is treated specially here:
This problem causes