Cosmos Emulator (windows, non-docker) is broken

[soenneker]

I don't know where to actually reach out so if this is wrong please point me in the right direction.

We're on the latest version of Windows, and we noticed today that it's not possible to actually connect to the emulator from the browser. We've tried reinstalling, resetting data, deleting all temp files, clearing windows performance counters, messing with the bindings etc.

In Chrome we get:

This site can’t be reached
The webpage at https://localhost:8081/_explorer/index.html might be temporarily down or it may have moved permanently to a new web address.
ERR_HTTP2_PROTOCOL_ERROR

or

ERR_CONNECTION_RESET

It feels like there was a Windows update or something that has messed with TLS and thus the handshake is failing.

It doesn't seem to be able to connect from the SDK either..

Thanks

[soenneker]

Update in case this helps others; I did get it going after seeing this article:

https://techcommunity.microsoft.com/blog/iis-support-blog/addressing-tls-1-3-compatibility-issues-in-iis-express-on-windows-11/4449362

The issue stems from the latest Windows 11 feature update's use of TLS 1.3, which doesn’t support the TLS renegotiation that Cosmos emulator uses to request client certificates after the initial handshake.

I executed these in elevated powershell and restarted after:

New-Item -Path "HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols" -Name "TLS 1.3" -ErrorAction SilentlyContinue

New-Item -Path "HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.3" -Name "Server" -ErrorAction SilentlyContinue

Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.3\Server" -Name "DisabledByDefault" -Value 1 -Type DWord

Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.3\Server" -Name "Enabled" -Value 0 -Type DWord

Works now.