解决方案

Please try to configure .NET Framework to support strong cryptography to use TLS 1.2 or enable TLS 1.0 from registry.

For configuring to support strong cryptography > press Windows key + R > type regedit > navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft.NetFramework\v4.0.30319 > add a new registry entry named SchUseStrongCrypto > set its type to DWord > set its value = 1.(or creating a new registry entry by using PS command)

For enabling TLS 1.0 > press Windows key + R > type regedit > navigate to Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\ > TLS 1.0 > Client > Enabled DWord value 1.

More details, see this doc: Configure for strong cryptography and this thread: Unable to login to VS 2013 upgrade 5.

参看

​​https://learn.microsoft.com/en-us/answers/questions/832154/visual-studio-2013-pro-the-online-service-is-not-a​​