Language server should give a helpful error message when started in ConstrainedLanguage mode

[sir-Higgins]

System Details

• Operating system name and version: Windows 10 1607 (14293.576)
• VS Code version: 1.8.1
• PowerShell extension version: 0.8.0
• Output from $PSVersionTable:

Name                           Value
----                           -----
PSVersion                      5.1.14393.576
PSEdition                      Desktop
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}
BuildVersion                   10.0.14393.576
CLRVersion                     4.0.30319.42000
WSManStackVersion              3.0
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1

Issue Description

When I open a .ps1 Script
there is three messages on top of the windows

• Could not start language service:
• Couldn't start client PowerShell Editor Service
• PowerShell could not be started, click 'Show Logs for more details.

Attached Logs

logs.zip

[daviwil]

Judging from the logs, it appears that your computer is configured with the ConstrainedLanguage mode which makes it impossible to start the language server. I'll add an extra check for this in the startup process so that I can give a helpful error message in this case.

[sir-Higgins]

ConstrainedLanguage is set in powershell when you activate applocker rules in windows 10 and powershell v5
https://www.sysadmins.lv/blog-en/powershell-50-and-applocker-when-security-doesnt-mean-security.aspx

I had an applocker rule that was still applied after a GPO change
https://technet.microsoft.com/en-us/library/hh310286(v=ws.10).aspx

After removing the applocker rules the language service started correctly.