Some bugs in the new cross-platform ilspy

[sonyps5201314]

1. Crash in older versions of ILSpy due to settings file incompatibility

After using the new cross-platform version of ILSpy (e.g., analyzing files or batch exporting PDBs) and closing it, launching an older version of ILSpy causes the older version to crash.

(Note: Based on the stack trace, it seems the new cross-platform version writes an empty or incompatible string for window bounds/rectangles into the shared ILSpy.xml config file, which causes System.Windows.Rect.Parse in the older WPF-based version to throw an exception).

---------------------------
Sorry, we crashed
---------------------------
System.InvalidOperationException: Premature string termination encountered while parsing "".

   at MS.Internal.TokenizerHelper.NextTokenRequired()
   at System.Windows.Rect.Parse(String source)
   at System.Windows.RectConverter.ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, Object value)
   at ICSharpCode.ILSpy.SessionSettings.FromString[T](String s, T defaultValue) in M:\Open_Code\ILSpy\ILSpy\SessionSettings.cs:line 170
   at ICSharpCode.ILSpy.SessionSettings.LoadFromXml(XElement section) in M:\Open_Code\ILSpy\ILSpy\SessionSettings.cs:line 56
   at ICSharpCode.ILSpyX.Settings.SettingsServiceBase.<GetSettings>b__6_0[T](Type _) in M:\Open_Code\ILSpy\ICSharpCode.ILSpyX\Settings\SettingsServiceBase.cs:line 53
   at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
   at ICSharpCode.ILSpyX.Settings.SettingsServiceBase.GetSettings[T]() in M:\Open_Code\ILSpy\ICSharpCode.ILSpyX\Settings\SettingsServiceBase.cs:line 48
   at ICSharpCode.ILSpy.Util.SettingsService.get_SessionSettings() in M:\Open_Code\ILSpy\ILSpy\Util\SettingsService.cs:line 48
   at ICSharpCode.ILSpy.App..ctor() in M:\Open_Code\ILSpy\ILSpy\App.xaml.cs:line 111
   at ICSharpCode.ILSpy.App.Main()
---------------------------
OK   
---------------------------

2. Drag and drop is not supported

The new cross-platform version of ILSpy doesn't seem to support dragging and dropping DLLs directly into the assembly list view. This feature was fully supported and worked well in previous versions.

[sonyps5201314]

@siegfriedpammer please take a look.

[christophwille]

@siegfriedpammer please take a look.

we do get notifications for issues and comments. No need to tag either of us within 20 minutes.

[siegfriedpammer]

@christophwille eec031a is already on release/10.1 and actually part of tag v10.1
@sonyps5201314 did you try the latest v10.1 release? The fix for SessionSettings.FromString is eec031a.

[sonyps5201314]

@siegfriedpammer I think you might have missed the core of the issue here. Fixing this in v10.1 doesn't really help, because the new version breaks the backward compatibility of the configuration file. Once the new version modifies the config, older versions fail to read it and crash on startup.

This is problematic because when users encounter a bug in a new release, we often revert to an older version to check if it's a regression. For instance, I only tried to launch the older version just now to see if the drag-and-drop bug existed there too, only to find that the older version wouldn't even start anymore.

Perhaps the perfect solution would be for the new version to migrate the settings into a newly named configuration file (e.g., ILSpyX.xml), leaving the old config file untouched so older versions can still function properly.

[christophwille]

Regarding item 2 I made the following recording which shows that d&d "works" only strictly as a list insert operation (which I totally agree is not the desired behavior as it is finnicky as can be)

ILSpy_O1GUZ7JXWD.mp4

[christophwille]

@sonyps5201314 please try again - d&d works (on my Windows machine) way better than in the above video (basically allows drop anywhere in the assembly list pane), but when it comes to settings: please put the changes for settings interop through its paces. Thanks.

[sonyps5201314]

The drag-and-drop issue is working fine now, but the configuration file backward compatibility issue is still not fully resolved.

---------------------------
Sorry, we crashed
---------------------------
System.InvalidOperationException: Premature string termination encountered while parsing "".

   at MS.Internal.TokenizerHelper.NextTokenRequired()
   at System.Windows.Rect.Parse(String source)
   at System.Windows.RectConverter.ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, Object value)
   at ICSharpCode.ILSpy.SessionSettings.FromString[T](String s, T defaultValue) in M:\Open_Code\ILSpy\ILSpy\SessionSettings.cs:line 170
   at ICSharpCode.ILSpy.SessionSettings.LoadFromXml(XElement section) in M:\Open_Code\ILSpy\ILSpy\SessionSettings.cs:line 56
   at ICSharpCode.ILSpyX.Settings.SettingsServiceBase.<GetSettings>b__6_0[T](Type _) in M:\Open_Code\ILSpy\ICSharpCode.ILSpyX\Settings\SettingsServiceBase.cs:line 53
   at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
   at ICSharpCode.ILSpyX.Settings.SettingsServiceBase.GetSettings[T]() in M:\Open_Code\ILSpy\ICSharpCode.ILSpyX\Settings\SettingsServiceBase.cs:line 48
   at ICSharpCode.ILSpy.Util.SettingsService.get_SessionSettings() in M:\Open_Code\ILSpy\ILSpy\Util\SettingsService.cs:line 48
   at ICSharpCode.ILSpy.App..ctor() in M:\Open_Code\ILSpy\ILSpy\App.xaml.cs:line 111
   at ICSharpCode.ILSpy.App.Main()
---------------------------
OK   
---------------------------

Below is the ILSpy.xml configuration file saved by the new version of ILSpy. As you can see, it still prevents the older version from launching:

<?xml version="1.0" encoding="utf-8"?>
<ILSpy version="11.0.0.8926">
  <SessionSettings>
    <FilterSettings>
      <ShowAPILevel>1</ShowAPILevel>
      <Language></Language>
      <LanguageVersion></LanguageVersion>
    </FilterSettings>
    <ActiveAssemblyList>Microsoft.ServiceHub.Framework_vs2026</ActiveAssemblyList>
    <ActiveTreeViewPath>
      <Node>C\x003A\x005CProgram\x0020Files\x005CMicrosoft\x0020Visual\x0020Studio\x005C2022\x005CEnterprise\x005CCommon7\x005CIDE\x005CCommonExtensions\x005CMicrosoft\x005CMicrosoft\x002EVisualStudio\x002ECopilot\x002EContracts\x005CMicrosoft\x002EVisualStudio\x002EExtensibility\x002ECopilot\x002EConfiguration\x002Edll</Node>
    </ActiveTreeViewPath>
    <WindowState>Maximized</WindowState>
    <WindowBounds Left="100" Top="100" Width="900" Height="600" />
    <Theme>Light</Theme>
    <MultiLineDocumentTabs>false</MultiLineDocumentTabs>
    <MouseWheelTogglesTabStripRows>true</MouseWheelTogglesTabStripRows>
  </SessionSettings>
  <UpdateSettings>
    <AutomaticUpdateCheckEnabled>true</AutomaticUpdateCheckEnabled>
    <LastSuccessfulUpdateCheck>2026-06-11T08:58:57.0997629Z</LastSuccessfulUpdateCheck>
  </UpdateSettings>
  <DisplaySettings Font="Consolas" FontSize="13.333333333333334" ShowLineNumbers="false" ShowMetadataTokens="false" ShowMetadataTokensInBase10="false" ShowDebugInfo="false" EnableWordWrap="false" SortResults="true" FoldBraces="false" ExpandMemberDefinitions="false" ExpandUsingDeclarations="false" IndentationUseTabs="true" IndentationSize="4" IndentationTabSize="4" HighlightMatchingBraces="true" HighlightCurrentLine="false" HideEmptyMetadataTables="true" UseNestedNamespaceNodes="false" ShowRawOffsetsAndBytesBeforeInstruction="false" StyleWindowTitleBar="false" DecodeCustomAttributeBlobs="false" />
  <DecompilerSettings NativeIntegers="true" NumericIntPtr="true" CovariantReturns="true" InitAccessors="true" RecordClasses="true" RecordStructs="true" StructDefaultConstructorsAndFieldInitializers="true" WithExpressions="true" UsePrimaryConstructorSyntax="true" FunctionPointers="true" ScopedRef="true" RequiredMembers="true" SwitchExpressions="true" FileScopedNamespaces="true" AnonymousMethods="true" AnonymousTypes="true" UseLambdaSyntax="true" ExpressionTrees="true" YieldReturn="true" Dynamic="true" AsyncAwait="true" AwaitInCatchFinally="true" AsyncEnumerator="true" DecimalConstants="true" FixedBuffers="true" StringConcat="true" LiftNullables="true" NullPropagation="true" AutomaticProperties="true" GetterOnlyAutomaticProperties="true" AutomaticEvents="true" UsingStatement="true" UseEnhancedUsing="true" AlwaysUseBraces="true" ForEachStatement="true" ForEachWithGetEnumeratorExtension="true" ParamsCollections="true" LockStatement="true" SwitchStatementOnString="true" SparseIntegerSwitch="true" UsingDeclarations="true" ExtensionMethods="true" QueryExpressions="true" UseImplicitMethodGroupConversion="true" UseObjectCreationOfGenericTypeParameter="true" AlwaysCastTargetsOfExplicitInterfaceImplementationCalls="false" AlwaysQualifyMemberReferences="false" AlwaysShowEnumMemberValues="false" UseDebugSymbols="true" ArrayInitializers="true" ObjectOrCollectionInitializers="true" DictionaryInitializers="true" ExtensionMethodsInCollectionInitializers="true" UseRefLocalsForAccurateOrderOfEvaluation="true" RefExtensionMethods="true" StringInterpolation="true" Utf8StringLiterals="true" SwitchOnReadOnlySpanChar="true" UnsignedRightShift="true" CheckedOperators="true" ShowXmlDocumentation="true" UseExpressionBodyForCalculatedGetterOnlyProperties="true" OutVariables="true" Discards="true" IntroduceRefModifiersOnStructs="true" IntroduceReadonlyAndInModifiers="true" IntroducePrivateProtectedAccessibility="true" ReadOnlyMethods="true" AsyncUsingAndForEachStatement="true" IntroduceUnmanagedConstraint="true" StackAllocInitializers="true" PatternBasedFixedStatement="true" TupleTypes="true" ThrowExpressions="true" TupleConversions="true" TupleComparisons="true" NamedArguments="true" NonTrailingNamedArguments="true" OptionalArguments="true" ExpandParamsArguments="true" LocalFunctions="true" Deconstruction="true" PatternMatching="true" RecursivePatternMatching="true" PatternCombinators="true" RelationalPatterns="true" StaticLocalFunctions="true" Ranges="true" NullableReferenceTypes="true" RemoveDeadCode="false" RemoveDeadStores="false" ApplyWindowsRuntimeProjections="true" AutoLoadAssemblyReferences="true" ForStatement="true" DoWhileStatement="true" RefReadOnlyParameters="true" UsePrimaryConstructorSyntaxForNonRecordTypes="true" InlineArrays="true" ExtensionMembers="true" FirstClassSpanTypes="true" RuntimeAsync="true" SeparateLocalVariableDeclarations="false" UseSdkStyleProjectFormat="true" UseNestedDirectoriesForNamespaces="false" AggressiveInlining="false" AlwaysUseGlobal="false" AlwaysMoveInitializer="false" SortCustomAttributes="false" CheckForOverflowUnderflow="false" />
</ILSpy>

[siegfriedpammer]

<WindowBounds Left="100" Top="100" Width="900" Height="600" />

this is no longer emitted on master... see

ILSpy/ILSpy/SessionSettings.cs

Lines 224 to 230 in 61bd014

	// Bounds as a CSV body ("L,T,W,H", the Rect TypeConverter format the WPF host used).
	// Keeping the legacy shape on write means a file written by this Avalonia build
	// can still be read by an older ILSpy 10.x install, and the file diff stays small
	// during the WPF -> Avalonia transition.
	section.Add(new XElement("WindowBounds", string.Format(
	CultureInfo.InvariantCulture, "{0},{1},{2},{3}",
	WindowPosition.X, WindowPosition.Y, WindowSize.Width, WindowSize.Height)));

[sonyps5201314]

Yes, my mistake. I only compiled the Debug build just now and accidentally ran yesterday's Release build, which caused the error. So this issue is indeed fixed.

Additionally, I noticed that you reverted ILSpy\Util\ShellHelper.cs. This unfortunately reintroduces the bug I previously fixed in 1f13b80.

The issue with multiple lingering explorer.exe processes has returned, and they are consuming a significant amount of user memory.

I also see that you've fully embraced AI and are using a powerful model like Claude Opus 4.7! With that in mind, the complex issues we discussed previously should be much easier to tackle now.

For instance:

• Collection expressions support (Ilspy fails to correctly generate the RECORD WITH statement for some complex records when targeting .NET Framework 4.7.2. #3593 (comment)): This is arguably the most critical one, because the lack of support completely prevents the decompiled code from being successfully recompiled.
• Imperfect PDB generation: Sometimes debugging still falls back to the Visual Studio disassembly view (The generated PDB has issues - stackframe switching is not supported. #3633).

[christophwille]

We will get back to tackling issues, however, atm we are still working on the last new UI feature plus internal infra enhancements.

[sonyps5201314]

2. Drag and drop is not supported

The new cross-platform version of ILSpy doesn't seem to support dragging and dropping DLLs directly into the assembly list view. This feature was fully supported and worked well in previous versions.

This issue hasn't been completely resolved. Dragging and dropping managed DLLs directly from the search results of third-party programs like FileLocator Pro still doesn't work. However, dragging those exact same files into VS Code opens them perfectly fine.

[christophwille]

Please create a follow-up new issue (ie "Drag & Drop from Non-Explorer Windows no longer works").