Omnisharp server startup exception: InvalidCast

Issue Description

When starting the OmniSharp server, it encounters a InvalidCastException and cannot start.

Steps to Reproduce

Have .NET Core 2.2 SDK installed, install .NET Core 3.0-preview, then remove .NET Core 3.0-preview, but the issue persists (even after uninstalling and re-installing the Omnisharp plugin). dotnet restore and dotnet run both work without issue.

Expected Behavior

Omnisharp server starts without exception.

Actual Behavior

Omnisharp server encounters an exception, and does not start.

Logs

OmniSharp log

Starting OmniSharp server at 9/11/2019, 2:29:46 PM Target: /Users/my-user/path/to/project

OmniSharp server started. Path: /Users/my-user/.vscode/extensions/ms-vscode.csharp-1.21.2/.omnisharp/1.32.19-beta.25/run PID: 5309

    Starting OmniSharp on MacOS 10.14.5 (x64)

    DotNetPath set to dotnet

    Located 1 MSBuild instance(s)
        1: StandAlone 15.0 - "/Users/my-user/.vscode/extensions/ms-vscode.csharp-1.21.2/.omnisharp/1.32.19-beta.25/omnisharp/.msbuild/Current/Bin"

    MSBUILD_EXE_PATH environment variable set to '/Users/my-user/.vscode/extensions/ms-vscode.csharp-1.21.2/.omnisharp/1.32.19-beta.25/omnisharp/.msbuild/Current/Bin/MSBuild.dll'

    Registered MSBuild instance: StandAlone 15.0 - "/Users/my-user/.vscode/extensions/ms-vscode.csharp-1.21.2/.omnisharp/1.32.19-beta.25/omnisharp/.msbuild/Current/Bin"
        MSBuildExtensionsPath = /Users/my-user/.vscode/extensions/ms-vscode.csharp-1.21.2/.omnisharp/1.32.19-beta.25/omnisharp/.msbuild
        BypassFrameworkInstallChecks = true
        CscToolPath = /Users/my-user/.vscode/extensions/ms-vscode.csharp-1.21.2/.omnisharp/1.32.19-beta.25/omnisharp/.msbuild/Current/Bin/Roslyn
        CscToolExe = csc.exe
        MSBuildToolsPath = /Users/my-user/.vscode/extensions/ms-vscode.csharp-1.21.2/.omnisharp/1.32.19-beta.25/omnisharp/.msbuild/Current/Bin
        TargetFrameworkRootPath = /Library/Frameworks/Mono.framework/Versions/4.0.4/lib/mono/xbuild-frameworks

System.InvalidCastException: Specified cast is not valid. at Roslyn.Utilities.EventMap.GetRegistries_NoLock[TEventHandler] (System.String eventName) [0x0001b] in <889d2020dcce4567aad80a068551b1d4>:0 at Roslyn.Utilities.EventMap.AddEventHandler[TEventHandler] (System.String eventName, TEventHandler eventHandler) [0x00015] in <889d2020dcce4567aad80a068551b1d4>:0 at Microsoft.CodeAnalysis.Workspace.add_WorkspaceChanged (System.EventHandler1[TEventArgs] value) [0x00000] in <889d2020dcce4567aad80a068551b1d4>:0 at Microsoft.AspNetCore.Razor.OmniSharpPlugin.PrecompiledRazorPageSuppressor..ctor (OmniSharp.OmniSharpWorkspace workspace) [0x0001b] in <8c6f4eb2e16d4051ba80a599aba81c54>:0 at (wrapper dynamic-method) System.Object.lambda_method(System.Runtime.CompilerServices.Closure,System.Composition.Hosting.Core.LifetimeContext,System.Composition.Hosting.Core.CompositionOperation) at System.Composition.Hosting.Core.LifetimeContext.GetOrCreate (System.Int32 sharingId, System.Composition.Hosting.Core.CompositionOperation operation, System.Composition.Hosting.Core.CompositeActivator creator) [0x000a8] in <8e026c716fc84f38aae28085eaaee9fc>:0 at System.Composition.TypedParts.ActivationFeatures.LifetimeFeature+<>c__DisplayClass1_0.<RewriteActivator>b__0 (System.Composition.Hosting.Core.LifetimeContext c, System.Composition.Hosting.Core.CompositionOperation o) [0x00011] in <9aac21a4a3f24063b2b8b59143acddfc>:0 at System.Composition.Hosting.Providers.ImportMany.ImportManyExportDescriptorProvider+<>c__DisplayClass3_21[TElement].<GetImportManyDescriptor>b__4 (System.Composition.Hosting.Core.ExportDescriptor e) [0x00006] in <8e026c716fc84f38aae28085eaaee9fc>:0 at System.Linq.Enumerable+SelectArrayIterator2[TSource,TResult].ToArray () [0x00012] in <28b7381f9e304c3eae9fa66907f89854>:0 at System.Linq.Enumerable.ToArray[TSource] (System.Collections.Generic.IEnumerable1[T] source) [0x0001f] in <28b7381f9e304c3eae9fa66907f89854>:0 at System.Composition.Hosting.Providers.ImportMany.ImportManyExportDescriptorProvider+<>c__DisplayClass3_11[TElement].<GetImportManyDescriptor>b__3 (System.Composition.Hosting.Core.LifetimeContext c, System.Composition.Hosting.Core.CompositionOperation o) [0x0002b] in <8e026c716fc84f38aae28085eaaee9fc>:0 at (wrapper dynamic-method) System.Object.lambda_method(System.Runtime.CompilerServices.Closure,System.Composition.Hosting.Core.LifetimeContext,System.Composition.Hosting.Core.CompositionOperation) at System.Composition.Hosting.Core.LifetimeContext.GetOrCreate (System.Int32 sharingId, System.Composition.Hosting.Core.CompositionOperation operation, System.Composition.Hosting.Core.CompositeActivator creator) [0x000a8] in <8e026c716fc84f38aae28085eaaee9fc>:0 at System.Composition.TypedParts.ActivationFeatures.LifetimeFeature+<>c__DisplayClass1_0.<RewriteActivator>b__0 (System.Composition.Hosting.Core.LifetimeContext c, System.Composition.Hosting.Core.CompositionOperation o) [0x00011] in <9aac21a4a3f24063b2b8b59143acddfc>:0 at System.Composition.Hosting.Providers.ImportMany.ImportManyExportDescriptorProvider+<>c__DisplayClass3_21[TElement].<GetImportManyDescriptor>b__4 (System.Composition.Hosting.Core.ExportDescriptor e) [0x00006] in <8e026c716fc84f38aae28085eaaee9fc>:0 at System.Linq.Enumerable+SelectArrayIterator2[TSource,TResult].ToArray () [0x00012] in <28b7381f9e304c3eae9fa66907f89854>:0 at System.Linq.Enumerable.ToArray[TSource] (System.Collections.Generic.IEnumerable1[T] source) [0x0001f] in <28b7381f9e304c3eae9fa66907f89854>:0 at System.Composition.Hosting.Providers.ImportMany.ImportManyExportDescriptorProvider+<>c__DisplayClass3_11[TElement].<GetImportManyDescriptor>b__3 (System.Composition.Hosting.Core.LifetimeContext c, System.Composition.Hosting.Core.CompositionOperation o) [0x0002b] in <8e026c716fc84f38aae28085eaaee9fc>:0 at System.Composition.Hosting.Core.CompositionOperation.Run (System.Composition.Hosting.Core.LifetimeContext outermostLifetimeContext, System.Composition.Hosting.Core.CompositeActivator compositionRootActivator) [0x0001c] in <8e026c716fc84f38aae28085eaaee9fc>:0 at System.Composition.Hosting.Core.LifetimeContext.TryGetExport (System.Composition.Hosting.Core.CompositionContract contract, System.Object& export) [0x0001d] in <8e026c716fc84f38aae28085eaaee9fc>:0 at System.Composition.Hosting.CompositionHost.TryGetExport (System.Composition.Hosting.Core.CompositionContract contract, System.Object& export) [0x00000] in <8e026c716fc84f38aae28085eaaee9fc>:0 at System.Composition.CompositionContext.GetExport (System.Composition.Hosting.Core.CompositionContract contract) [0x00000] in <12675e53c8854b48abd187539ce374db>:0 at System.Composition.CompositionContext.GetExports (System.Type exportType, System.String contractName) [0x00023] in <12675e53c8854b48abd187539ce374db>:0 at System.Composition.CompositionContext.GetExports[TExport] (System.String contractName) [0x00000] in <12675e53c8854b48abd187539ce374db>:0 at System.Composition.CompositionContext.GetExports[TExport] () [0x00000] in <12675e53c8854b48abd187539ce374db>:0 at OmniSharp.Stdio.Host.Initialize () [0x0001e] in <3cc12c7c00f344b08c42dfac73970669>:0 at OmniSharp.Stdio.Host..ctor (System.IO.TextReader input, OmniSharp.Services.ISharedTextWriter writer, OmniSharp.IOmniSharpEnvironment environment, System.IServiceProvider serviceProvider, OmniSharp.CompositionHostBuilder compositionHostBuilder, Microsoft.Extensions.Logging.ILoggerFactory loggerFactory, System.Threading.CancellationTokenSource cancellationTokenSource) [0x00070] in <3cc12c7c00f344b08c42dfac73970669>:0 at OmniSharp.Stdio.Driver.Program+<>c__DisplayClass0_1.<Main>b__1 () [0x00138] in <0a1d4b17e42e41ff8dffd9ad6b26ea3a>:0 at OmniSharp.CommandLineApplication+<>c__DisplayClass11_0.<OnExecute>b__0 () [0x0000b] in <26e431e77bba4574aea35bb4bb3374a8>:0 at McMaster.Extensions.CommandLineUtils.CommandLineApplication.Execute (System.String[] args) [0x00039] in <344a1e8cd6594b17b1e01f8df6ae8827>:0 at OmniSharp.CommandLineApplication.Execute (System.Collections.Generic.IEnumerable1[T] args) [0x00042] in <26e431e77bba4574aea35bb4bb3374a8>:0 at OmniSharp.Stdio.Driver.Program+<>c__DisplayClass0_0.<Main>b__0 () [0x00028] in <0a1d4b17e42e41ff8dffd9ad6b26ea3a>:0 at OmniSharp.HostHelpers.Start (System.Func`1[TResult] action) [0x0001c] in <26e431e77bba4574aea35bb4bb3374a8>:0

C# log

Post the output from Output-->C# here

Environment information

VSCode version: 1.38.0 C# Extension: 1.21.2

Mono Information

OmniSharp using built-in mono

Dotnet Information

.NET Core SDK (reflecting any global.json): Version: 2.2.402 Commit: c7f2f96116

Runtime Environment: OS Name: Mac OS X OS Version: 10.14 OS Platform: Darwin RID: osx.10.14-x64 Base Path: /usr/local/share/dotnet/sdk/2.2.402/

Host (useful for support): Version: 3.0.0-preview9-19423-09 Commit: 2be172345a

.NET Core SDKs installed: 2.0.0 [/usr/local/share/dotnet/sdk] 2.1.3 [/usr/local/share/dotnet/sdk] 2.1.302 [/usr/local/share/dotnet/sdk] 2.1.403 [/usr/local/share/dotnet/sdk] 2.2.103 [/usr/local/share/dotnet/sdk] 2.2.104 [/usr/local/share/dotnet/sdk] 2.2.402 [/usr/local/share/dotnet/sdk]

.NET Core runtimes installed: Microsoft.AspNetCore.All 2.1.2 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.All] Microsoft.AspNetCore.All 2.1.5 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.All] Microsoft.AspNetCore.All 2.2.1 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.All] Microsoft.AspNetCore.All 2.2.2 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.All] Microsoft.AspNetCore.All 2.2.7 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.All] Microsoft.AspNetCore.App 2.1.2 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App] Microsoft.AspNetCore.App 2.1.5 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App] Microsoft.AspNetCore.App 2.2.1 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App] Microsoft.AspNetCore.App 2.2.2 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App] Microsoft.AspNetCore.App 2.2.7 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App] Microsoft.NETCore.App 2.0.0 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App] Microsoft.NETCore.App 2.0.4 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App] Microsoft.NETCore.App 2.1.2 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App] Microsoft.NETCore.App 2.1.5 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App] Microsoft.NETCore.App 2.2.1 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App] Microsoft.NETCore.App 2.2.2 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App] Microsoft.NETCore.App 2.2.7 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]

To install additional .NET Core runtimes or SDKs: https://aka.ms/dotnet-download

Visual Studio Code Extensions

Extension	Author	Version
auto-rename-tag	formulahendry	0.1.0
code-spell-checker	streetsidesoftware	1.7.18
csharp	ms-vscode	1.21.2
npm-intellisense	christian-kohler	1.3.0
prettier-vscode	esbenp	2.2.2
rainbow-csv	mechatroner	1.3.1
relativepath	john681611	0.1.2
sublime-keybindings	ms-vscode	4.0.3
vscode-eslint	dbaeumer	1.9.1
vscode-icons	vscode-icons-team	9.3.0
vscode-nuget-package-manager	jmrog	1.1.6

[filipw]

or try removing “omnisharp.path”: “latest” from the settings

[mattheworres]

@filipw thanks! that must’ve done it, i saw that beta25 was specified in my settings.json, as soon as I deleted that, it asked if I wanted to restart O#, I did, and it’s back to working again.

Thanks!