Unable to configure HTTPS endpoint. No server certificate was specified, and the default developer certificate could not be found
URL使用http就没这问题。如果使用https，没弄好的话，就有这个问题。
解法：
步骤1
运行下面两行：
dotnet dev-certs https --clean
dotnet dev-certs https --trust
步骤2
如果步骤1来创建certificate, 但还是表示“找不到”。
则可能是dotnet dev-certs https --clean没能给删干净，这样可以手动去删：(参考)
删除所有Friendly名字叫ASP.NET Core的localhost certificates
Current User > Personal > Certificates
Current User > Trusted root certification authorities > Certificates
