Hello Mark,

Does the CSp.log show an authorization header with something like this?

Authorization: NTLM TlRMTVNTU... 

When NTLM is in place the client sends the authorization header prior to the body post. However, the CSP gateway is not expecting this, hence the error.

This may be resolved if you are on v2018+ as described here,
https://docs.intersystems.com/latest/csp/docbook/Doc.View.cls?KEY=GCRN_n...

Otherwise, the way this has generally been resolved in the past is to modify the NTLM settings.

One way this has been done is to change the NTLM authentication to "Authentication delegated - may authenticate directly”.

Regards,

Rupert