Betfair informed us of the following:-
Please be aware that from 7th February, the only protocol for securing the communication Betfair servers and web browsers will be TLS 1.2. Older versions (TLS.1.0, TLS.1.1 or SSLv3) will no longer work.
So Betfair's API server will no longer support anything below TLS 1.2 for secure traffic.
This means that Version 1.3.0.37a will no longer work as of 7th February 2019. It will auto update to version 1.3.0.39.
You can install this update Here if the auto update fails.
Please note this also means that you will no longer be able to use the software on Windows XP or Windows Vista.
Regards,
Mark