support OpenSSL 1.1.x or higher. Using newer DLLs meant for Indy 10 will frequently trigger this error. Google Groups 2. Where to Get the DLLs
Ensure you have a TIdSSLIOHandlerSocket component on your form and that your TIdHTTP (or other Indy component) has its IOHandler property linked to it [4, 5]. Delphi 7 Indy 9 Could Not Load Ssl Library