Probably a bug of Microsoft Python Language Server

[jerryc05]

Environment data

• VS Code version: 1.31.0 insider
• Extension version (available under the Extensions sidebar): 2018.12.1
• OS and version: Win10 1809
• Python version (& distribution if applicable, e.g. Anaconda): Anaconda
• Type of virtual environment used (N/A | venv | virtualenv | conda | ...): conda
• Relevant/affected Python packages and their versions: N/A

Expected behaviour

no error output

Actual behaviour

error output after opening a .py file

Steps to reproduce:

1. open a .py file and wait a few second

Logs

Output for Python in the Output panel (View→Output, change the drop-down the upper-right of the Output panel to Python)

Microsoft Python Language Server version 0.1.72.0
Initializing for [hidden]\python.exe
[Error - 12:32:39 AM] System.NullReferenceException: Object reference not set to an instance of an object.
   at Microsoft.PythonTools.Analysis.AnalysisSet.Split[T](IAnalysisSet set, IReadOnlyList`1& ofType, IAnalysisSet& rest)
   at Microsoft.PythonTools.Analysis.Analyzer.ExpressionEvaluatorAnnotationConverter.FinalizeNames(IAnalysisSet types)
   at Microsoft.PythonTools.Analysis.Analyzer.ExpressionEvaluatorAnnotationConverter.MakeGeneric(IAnalysisSet baseType, IReadOnlyList`1 args)
   at Microsoft.PythonTools.Parsing.Ast.TypeAnnotation.Walker.MakeGenericOp.Apply[T](TypeAnnotationConverter`1 converter, Stack`1 stack)
   at Microsoft.PythonTools.Parsing.Ast.TypeAnnotation.Walker.GetResult[T](TypeAnnotationConverter`1 converter)
   at Microsoft.PythonTools.Analysis.Values.TypingTypeInfo.<>c__DisplayClass8_0.<GetIndex>b__0(Node n)
   at Microsoft.PythonTools.Analysis.Analyzer.InterpreterScope.GetOrMakeNodeValue(Node node, NodeValueKind kind, Func`2 maker)
   at Microsoft.PythonTools.Analysis.AnalysisValueSetExtensions.GetIndex(IAnalysisSet self, Node node, AnalysisUnit unit, IAnalysisSet index)
   at Microsoft.PythonTools.Analysis.Analyzer.ExpressionEvaluator.EvaluateWorker(Node node)
   at Microsoft.PythonTools.Analysis.Analyzer.DDG.Walk(ReturnStatement node)
   at Microsoft.PythonTools.Parsing.Ast.ReturnStatement.Walk(PythonWalker walker)
   at Microsoft.PythonTools.Analysis.Analyzer.DDG.Walk(SuiteStatement node)
   at Microsoft.PythonTools.Parsing.Ast.SuiteStatement.Walk(PythonWalker walker)
   at Microsoft.PythonTools.Analysis.Analyzer.FunctionAnalysisUnit.AnalyzeWorker(DDG ddg, CancellationToken cancel)
   at Microsoft.PythonTools.Analysis.Analyzer.DDG.Analyze(Deque`1 queue, CancellationToken cancel, Action`1 reportQueueSize, Int32 reportQueueInterval)
   at Microsoft.PythonTools.Analysis.PythonAnalyzer.AnalyzeQueuedEntries(CancellationToken cancel)
   at Microsoft.PythonTools.Intellisense.AnalysisQueue.GroupAnalysis.Analyze(CancellationToken cancel)
   at Microsoft.PythonTools.Intellisense.AnalysisQueue.HandleAnalyzable(IAnalyzable item, AnalysisPriority priority, CancellationToken cancellationToken)
   at Microsoft.PythonTools.Intellisense.AnalysisQueue.ConsumerLoop()
##########Linting Output - pylint##########

Output from Console under the Developer Tools panel (toggle Developer Tools on under Help; turn on source maps to make any tracebacks be useful by running Enable source map support for extension debugging)

XXX

[karrtikr]

You are using Microsoft Python Language Server version 0.1.72.0 as visible in Output panel, try updating to the latest version.
Check Issue #3977 with instructions on how to install the latest version of the language server:

[jerryc05]

@karrtikr Hi, I upgraded Language Server to the latest 0.1.75.0 and the problem still exists. I even tried to change to the python distribution from python.org, but nothing changed. Any clue to fix it? thanks.

[karrtikr]

@jerryc05 Try reinstalling the vscode, Python extension to the latest version as well. There might be compatibility issues.

You can try troubleshooting using PYTHON_INTERACTIVE_TROUBLESHOOTING.md guide.

[jerryc05]

@karrtikr Hi thank you for your advice but unfortunatelly it still did not work. Maybe I should submit an issue to the ms language server repo.