Problem creating SM59 connection to HTTPS

Hello -

I am trying to connect to an external REST API from SAP over HTTPS. In SAP I have created a connection in SM59 with the host/prefix & port. The vendor has indicated that they do not issue out SSL certificates, and that we must use basic authentication (username/password) to authenticate.

In SM59 when I set SSL to inactive and test the connection, I get a 400 Bad Request - The plain HTTP request was sent to HTTPS port message. When I set to SSL active I get an ICM_HTTP_SSL_ERROR which I assume indicates that there is an issue with the SSL certificate, yet we do not need an SSL certificate to connec. Thus I am not sure what to do in order to make SAP connect?

Has anyone faced this issue that can offer any advice? Below is the error from the ICM monitor.

[Thr 16924] *** ERROR during SecudeSSL_SessionStart() from SSL_connect()==SSL_ERROR_SSL

[Thr 16924]    session uses PSE file "K:\usr\sap\DEV\DVEBMGS00\sec\SAPSSLA.pse"

[Thr 16924] SecudeSSL_SessionStart: SSL_connect() failed

[Thr 16924]   secude_error 9 (0x00000009) = "the verification of the server's certificate chain failed"

[Thr 16924] >>            Begin of Secude-SSL Errorstack            >>

[Thr 16924] ERROR in ssl3_get_server_certificate: (9/0x0009) the verification of the server's certificate chain failed #

[Thr 16924] ERROR in af_verify_Certificates: (27/0x001b) Chain of certificates is incomplete : "EMAIL=info@valicert.com, CN=http://w

[Thr 16924] ERROR in get_path: (27/0x001b) Found root certificate of <EMAIL=info@valicert.com, CN=http://www.valicert.com/, OU=ValiC

[Thr 16924] ERROR in verify_with_PKs: (27/0x001b) Found root certificate of <EMAIL=info@valicert.com, CN=http://www.valicert.com/, O

[Thr 16924] <<            End of Secude-SSL Errorstack

[Thr 16924]   SSL_get_state() returned 0x00002131 "SSLv3 read server certificate B"

[Thr 16924]   SSL NI-sock: local=10.10.7.78:62645  peer=131.103.27.179:443

[Thr 16924] <<- ERROR: SapSSLSessionStart(sssl_hdl=000000000C170B10)==SSSLERR_SSL_CONNECT

[Thr 16924] *** ERROR => IcmConnInitClientSSL: SapSSLSessionStart failed (-57): SSSLERR_SSL_CONNECT {005a66f8} [icxxconn.c 1957]