Having certificate issues when calling Web API from Web App - ssl

Question

I am developing a web api and a web app locally. I am having trouble calling the web api from the web app.
When I call it I keep getting the error: "The remote certificate is invalid according to the validation procedure."
Both apps are built with ASP.Net Core and are running on kestrel. The webapp is callable as https://mylibrary.com:5003 and the Web API is callable as https://api.mylibrary.com:5001.
How can I get them working together with valid certificates?
Edit: Come to realise that the issue is that the apps are using localhost certs by default. I want to be able to use my own self signed cert.
If someone can point me to somewhere that explains how to set up two apps to use a self-signed certificate in .net core web projects please do :)

Answer 1

If you need to work around the cert validation using HttpClient, you could do it by creating a HttpClientHandler and passing it to HttpClient as per Rohit Jangid's answer to The SSL connection could not be established
HttpClientHandler clientHandler = new HttpClientHandler();
clientHandler.ServerCertificateCustomValidationCallback = (sender, cert, chain, sslPolicyErrors) => { return true; };
// Pass the handler to httpclient(from you are calling api)
HttpClient client = new HttpClient(clientHandler)
Avoid accidentally circumventing certificate validation in production by checking if it is in development environment:
HttpClient httpClient = new HttpClient();
if (env.IsDevelopment())
{
HttpClientHandler clientHandler = new HttpClientHandler();
clientHandler.ServerCertificateCustomValidationCallback = (sender, cert, chain, ssl) => { return true; };
httpClient = new HttpClient(clientHandler);
}
Inject information about webhostenvironment by injecting it in the handler/action:
public async Task OnGet([FromServices] IWebHostEnvironment env)

Answer 2

Please try to use RestSharp library to make the webapi request and set the cert validation to true. see here
or you can install the dotnet dev certs by executing dotnet dev-certs https --trust in a command promt or powershell