I have create a ASP.net webform with a reportview control. Tested this on the IIS server and working 100%. I then, on our linux box changed the NGINX config, added a proxy_pass pointing to the IIS website hosting the asp.net form. On the linux box, is hosted a Net core 3.1 website. In this website there is an IFrame that points to the asp.net webform address. When the IFRame gets loaded, I keep getting below error – please remember it is working on IIS.