We are hosting our applications on premises in an environment that utilizes a protected proxy server for all connections. We enabled the proxy server in our app by adding the http.proxyHost, http.proxyPort, http.proxyUser and http.proxyPassword to our custom Mendix settings. While this seems to work, everytime that we do a rest call from our application to another application we receive the following 2 warnings. NEGOTIATE authentication error: No valid credentials provided (Mechanism level: No valid credentials provided (Mechanism level: Failed to find any Kerberos tgt)) NTLM authentication error: Credentials cannot be used for NTLM authentication: org.apache.http.auth.UsernamePasswordCredentials What seems to happen is that runtime tries to authenticate to the proxy server, first via Kerberos then via NTLM before it falls back to Basic Authentication. Since the amount of webservice calls can become significant these warnings are flooding our logs. How can we prevent the runtime from using Kerberos and NTLM?