System.IO.FileNotFoundException: Could not load file or assembly 'System.Reflection.Emit.ILGeneration

[kodalipraveen]

Issue Type: Bug

The below Error keeps coming up in Output->Pyhton when working on python files.

[Error - 11:45:56 AM] System.TypeInitializationException: The type initializer for 'Microsoft.PythonTools.Analysis.Indexing.SymbolIndexWalker' threw an exception. ---> System.IO.FileNotFoundException: Could not load file or assembly 'System.Reflection.Emit.ILGeneration, Version=4.0.3.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. The system cannot find the file specified.

at System.Text.RegularExpressions.Regex.Compile(RegexCode code, RegexOptions roptions)
at System.Text.RegularExpressions.Regex..ctor(String pattern, RegexOptions options, TimeSpan matchTimeout, Boolean addToCache)
at System.Text.RegularExpressions.Regex..ctor(String pattern, RegexOptions options)
at Microsoft.PythonTools.Analysis.Indexing.SymbolIndexWalker..cctor()
--- End of inner exception stack trace ---
at Microsoft.PythonTools.Analysis.Indexing.SymbolIndexWalker.Walk(FunctionDefinition node)
at Microsoft.PythonTools.Parsing.Ast.FunctionDefinition.Walk(PythonWalker walker)
at Microsoft.PythonTools.Parsing.Ast.SuiteStatement.Walk(PythonWalker walker)
at Microsoft.PythonTools.Analysis.Indexing.SymbolIndexWalker.Walk(ClassDefinition node)
at Microsoft.PythonTools.Parsing.Ast.ClassDefinition.Walk(PythonWalker walker)
at Microsoft.PythonTools.Parsing.Ast.SuiteStatement.Walk(PythonWalker walker)
at Microsoft.PythonTools.Parsing.Ast.PythonAst.Walk(PythonWalker walker)
at Microsoft.PythonTools.Analysis.Indexing.SymbolIndex.UpdateParseTree(Uri uri, PythonAst ast)
at Microsoft.Python.LanguageServer.Implementation.Server.UpdateSymbolIndex(Object sender, ParseCompleteEventArgs args)
at Microsoft.Python.LanguageServer.Implementation.Server.OnDocumentChangeProcessingComplete(IDocument doc, VersionCookie vc, Boolean enqueueForAnalysis, AnalysisPriority priority, IDisposable disposeWhenEnqueued)

Extension version: 2019.2.5433
VS Code version: Code 1.31.1 (1b8e8302e405050205e69b59abb3559592bb9e60, 2019-02-12T02:16:38.656Z)
OS version: Darwin x64 18.2.0

[DonJayamanne]

Please could you uninstall the extension, quit vs code (this will ensure the extension folder gets deleted).
Next open vscode and reinstall the extension and try again.
If this doesn't fix is, please do let us know and we'll be glad to reopen the issue.

[kodalipraveen]

After a restart of the mac laptop, the issue got resolved. I did not have to uninstall anything.
Thanks for the support.