对我来说，问题实际上是我把机器弄坏了。配置和看起来像VS不能有一个连接 我在machine.config中添加了以下代码行

<!--
<system.net>
 <defaultProxy>
  <proxy autoDetect="false" bypassonlocal="false" proxyaddress="http://127.0.0.1:8888" usesystemdefault="false" />
 </defaultProxy>
</system.net>
<!--
-->

将前一节替换为:

<!--
<system.net>
 <defaultProxy>
  <proxy autoDetect="false" bypassonlocal="false" proxyaddress="http://127.0.0.1:8888" usesystemdefault="false" />
 </defaultProxy>
</system.net>
-->

VS开始工作。

登录后，30天的试用期就会消失!

“如果你已经登录了，注销，然后再登录。” -b1nary.atr0phy

VS 17社区版是免费的。你只需要用你的微软账户登录，一切就会恢复正常。

就我而言，我已经注册了。所以我不得不签出，然后再签入。

在西班牙语中，Cerrar会议是签字退出。

对于VS2019，我可以用我的github账户注册:

然后它会发送密码到你的电子邮件，你就可以签名了。

I had this problem. Signing in or pressing the "Check for an updated license" link did not work for me. My solution was to restart Visual Studio, try again (sign in and check for license). Restart Visual Studio, try again. I had to do this several times and then it worked! (I also tried pressing the "File" menu that is available for a short period of time before the annoying request window appears again.) Maybe you just don't get connected to the server or the server itself doesn't update its database fast enough.