Bug 45248 - "Couldn't connect to {build hostname}. Please try again." after downgrading Xamarin
Summary: "Couldn't connect to {build hostname}. Please try again." after downgrading X...
Alias: None
Product: Visual Studio Extensions
Classification: Xamarin
Component: XMA ()
Version: 4.2.0 (C8)
Hardware: PC Windows
: --- normal
Target Milestone: ---
Assignee: Bugzilla
Depends on:
Reported: 2016-10-10 19:58 UTC by Kyle White
Modified: 2016-12-27 21:45 UTC (History)
3 users (show)

Is this bug a regression?: ---
Last known good build:

verbose logs (10.61 KB, application/x-zip-compressed)
2016-10-10 19:58 UTC, Kyle White

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Description Kyle White 2016-10-10 19:58:59 UTC
Created attachment 17960 [details]
verbose logs

I was running master/C9 builds on both my mac and pc and everything was working fine (XMA connected with full support). I downgraded both the mac and the pc to Cycle8 builds and suddenly the pc was unable to connect to the mac. 

The Xamarin Output window only says these three lines:

Starting connection to Mac kyles-mbp...
Couldn't connect to kyles-mbp. Please try again.
Disconnected from Mac kyles-mbp (

When it happened, I was running devenv via "devenv /log" so verbose logs should be attached. There was _no_ new logs on the mac host in ~/Library/Logs/Xamarin-4.2/..

Next, I went to the XMA dialog in VS and chose "Forget this Mac" for 'kyles-mbp' and then tried connecting again, and it magically worked.

Xamarin.VisualStudio.IOS.Messaging.State.ServerStateContext Information: 0 : [2016-10-10 15:38:49.5785] MacServer State transition from DisconnectedState to SshConnectingState on kyles-mbp (
Xamarin.Messaging.VisualStudio.MessagingService Information: 0 : [2016-10-10 15:38:50.5883] Starting connection to Mac kyles-mbp...
Xamarin.VisualStudio.IOS.Messaging.State.DisconnectedState Error: 0 : [2016-10-10 15:38:52.4246] username
System.ArgumentException: username
   at Renci.SshNet.AuthenticationMethod..ctor(String username)
   at Xamarin.Messaging.Client.Ssh.MessagingAuthenticationMethod..ctor(String username, Func`1 passwordProvider, ISshInformationProvider sshInformationProvider)
   at Xamarin.Messaging.VisualStudio.MessagingService.GetMessagingConnection(Int32 boundPort, Func`1 passwordProvider, ISshInformationProvider sshInformationProvider)
   at Xamarin.Messaging.VisualStudio.MessagingService.<ConnectAsync>d__71.MoveNext()
Xamarin.VisualStudio.IOS.Messaging.State.DisconnectedState Error: 0 : [2016-10-10 15:38:52.7156] Couldn't connect to kyles-mbp. Please try again.
Xamarin.VisualStudio.IOS.Messaging.State.ServerStateContext Information: 0 : [2016-10-10 15:38:52.9066] MacServer State transition from SshConnectingState to DisconnectedState on kyles-mbp (
Xamarin.VisualStudio.IOS.Messaging.State.ServerStateContext Information: 0 : [2016-10-10 15:38:53.0896] Disconnected from Mac kyles-mbp (
Comment 1 Ben Beckley 2016-10-10 21:13:33 UTC
I was able to reproduce this when downgrading from (master) to (xvs-win-cycle8-sr0)

IDE Log: https://gist.github.com/BenBeckley/d6aa1ff4a4e7261f3782f50f3ecb5df6
Comment 2 Jose Gallardo 2016-12-27 21:45:08 UTC
This is a known issue, and the way to avoid it is to forget the mac and add it again.
Unfortunately, it cannot be avoided and is listed already as part of the release notes.