ASP.net Core web application gives error: System.Net.Http.WinHttpException: A security error occured

I have an ASP.Net Cor web application that makes calls to a separate ASP.Net API application. It's a simple search, but when I click the button on the page to make the call, the page just goes blank. I checked by error log, and I am seeing this error:

System.Net.Http.WinHttpException: A security error occurred.

It is pointing to a specific line of code:

HttpResponseMessage Res = await client.GetAsync("api/search?item=" + searchterm);

Any help is appreciated. Nothing I've searched has come up with anything yet.