错误提示：
Microsoft.AspNetCore.Server.Kestrel|Unable to start Kestrel.
Unhandled exception. System.InvalidOperationException: Unable to configure HTTPS
endpoint. No server certificate was specified, and the default developer certif
icate could not be found or is out of date.
To generate a developer certificate run 'dotnet dev-certs https'. To trust the c
ertificate (Windows and macOS only) run 'dotnet dev-certs https --trust'.
For more information on configuring HTTPS see https://go.microsoft.com/fwlink/?l
inkid=848054.
这个问题主要是core项目使用了HTTPS协议，但是没有安装相关证书
仔细查看提示执行dotnet dev-certs https --trust即可。
执行完后提示：
欢迎使用 .NET Core 3.1!
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SDK 版本: 3.1.101
遥测
---------
.NET Core 工具收集使用数据，以帮助我们改善你的体验。数据是匿名的。它由 Microsoft
收集并与社区共享。你可以通过使用喜欢的 shell 将 DOTNET_CLI_TELEMETRY_OPTOUT 环
境变量设置为 "1" 或 "true" 来选择退出遥测。
阅读有关 .NET Core CLI 工具遥测的更多信息: https://aka.ms/dotnet-cli-telemetry
----------------
查看文档: https://aka.ms/dotnet-docs
通过 GitHub 报告问题和查找源: https://github.com/dotnet/core
查找最新功能: https://aka.ms/dotnet-whats-new
了解已安装的 HTTPS 开发者证书: https://aka.ms/aspnet-core-https
使用 "dotnet --help" 查看可用命令或访问: https://aka.ms/dotnet-cli-docs
编写你的第一个应用: https://aka.ms/first-net-core-app
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Trusting the HTTPS development certificate was requested. A confirmation prompt
will be displayed if the certificate was not previously trusted. Click yes on th
e prompt to trust the certificate.
A valid HTTPS certificate is already present.