runtime: Corrupted environment block causes GetEnvironmentVariables to throw ArgumentException: Item has already been added.

From @livarcocc on June 12, 2018 21:11

From @shaunluttin on June 11, 2018 23:30

Steps to reproduce

Install .NET Core SDK 2.1.300

Open a PowerShell session and run this:

$scope = [System.EnvironmentVariableTarget]::User;
[System.Environment]::SetEnvironmentVariable("TMP", "Foobarbaz", $scope); 
[System.Environment]::SetEnvironmentVariable("TEMP", "Foobarbaz", $scope);

Open another PowerShell session and run dotnet new.

Expected behavior

The CLI will show the standard dotnet new output.

Actual behavior

PS C:\dev> dotnet new                                                                                                                                                                                      
System.ArgumentException: Item has already been added. Key in dictionary: 'Foobarbaz'  Key being added: 'Foobarbaz'                                                                                        
   at System.Collections.Hashtable.Insert(Object key, Object nvalue, Boolean add)                                                                                                                          
   at System.Environment.ToHashtable(IEnumerable`1 pairs)                                                                                                                                                  
   at System.Environment.GetEnvironmentVariables()                                                                                                                                                         
   at Microsoft.TemplateEngine.Utils.EngineEnvironmentSettings.DefaultEnvironment..ctor()                                                                                                                  
   at Microsoft.TemplateEngine.Utils.EngineEnvironmentSettings..ctor(ITemplateEngineHost host, Func`2 settingsLoaderFactory, String hiveLocation)                                                          
   at Microsoft.TemplateEngine.Cli.New3Command..ctor(String commandName, ITemplateEngineHost host, ITelemetryLogger telemetryLogger, Action`2 onFirstRun, INewCommandInput commandInput, String hivePath)  
   at Microsoft.TemplateEngine.Cli.New3Command.ActualRun(String commandName, ITemplateEngineHost host, ITelemetryLogger telemetryLogger, Action`2 onFirstRun, String[] args, String hivePath)              
   at Microsoft.TemplateEngine.Cli.New3Command.Run(String commandName, ITemplateEngineHost host, ITelemetryLogger telemetryLogger, Action`2 onFirstRun, String[] args, String hivePath)                    
   at Microsoft.TemplateEngine.Cli.New3Command.Run(String commandName, ITemplateEngineHost host, ITelemetryLogger telemetryLogger, Action`2 onFirstRun, String[] args)                                     
   at Microsoft.DotNet.Tools.New.NewCommandShim.Run(String[] args)                                                                                                                                         
   at Microsoft.DotNet.Cli.Program.ProcessArgs(String[] args, ITelemetry telemetryClient)                                                                                                                  
   at Microsoft.DotNet.Cli.Program.Main(String[] args)                                                                                                                                                     

Environment data

dotnet --info output:

.NET Core SDK (reflecting any global.json):                                                  
 Version:   2.1.300                                                                          
 Commit:    adab45bf0c                                                                       
                                                                                             
Runtime Environment:                                                                         
 OS Name:     Windows                                                                        
 OS Version:  10.0.16299                                                                     
 OS Platform: Windows                                                                        
 RID:         win10-x64                                                                      
 Base Path:   C:\Program Files\dotnet\sdk\2.1.300\                                           
                                                                                             
Host (useful for support):                                                                   
  Version: 2.1.0                                                                             
  Commit:  caa7b7e2ba                                                                        
                                                                                             
.NET Core SDKs installed:                                                                    
  2.1.4 [C:\Program Files\dotnet\sdk]                                                        
  2.1.300 [C:\Program Files\dotnet\sdk]                                                      
                                                                                             
.NET Core runtimes installed:                                                                
  Microsoft.AspNetCore.All 2.1.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]   
  Microsoft.AspNetCore.App 2.1.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]   
  Microsoft.NETCore.App 2.1.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]         
                                                                                             
To install additional .NET Core runtimes or SDKs:                                            
  https://aka.ms/dotnet-download                                                             

Other Notes

The actual situation is that we had the following two environmental variables:

TMP                            C:\Users\bigfo\AppData\Local\Temp
TEMP                           C:\Users\bigfo\AppData\Local\Temp

Our fix was to remove the TMP variable.

[System.Environment]::SetEnvironmentVariable("TMP", "", [System.EnvironmentVariableTarget]::User)

Copied from original issue: dotnet/cli#9461

Copied from original issue: dotnet/templating#1563