VS 2026 error bar on .razor file: Unexpected false - file IndentBlockOperation.cs

I just ran into a razor error when doing ctrl-k-ctrl-d in VS 18.3.0

StreamJsonRpc.RemoteInvocationException: Unexpected false - file IndentBlockOperation.cs line 38
at StreamJsonRpc.JsonRpc.d__1711.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at Microsoft.CodeAnalysis.Remote.BrokeredServiceConnection1.d__181.MoveNext() RPC server exception: System.InvalidOperationException: Unexpected false - file IndentBlockOperation.cs line 38 at Microsoft.CodeAnalysis.Contract.Fail(String message, Int32 lineNumber, String filePath) at Microsoft.CodeAnalysis.Formatting.Rules.IndentBlockOperation..ctor(SyntaxToken baseToken, SyntaxToken startToken, SyntaxToken endToken, TextSpan textSpan, Int32 indentationDelta, IndentBlockOption option) at Microsoft.CodeAnalysis.CSharp.Formatting.IndentBlockFormattingRule.AddBracketIndentationOperation(List1 list, SyntaxNode node)
at Microsoft.CodeAnalysis.CSharp.Formatting.IndentBlockFormattingRule.AddIndentBlockOperations(List1 list, SyntaxNode node, NextIndentBlockOperationAction& nextOperation) at Microsoft.CodeAnalysis.Formatting.Rules.NextIndentBlockOperationAction.Invoke() at Microsoft.CodeAnalysis.CSharp.Formatting.IndentUserSettingsFormattingRule.AddIndentBlockOperations(List1 list, SyntaxNode node, NextIndentBlockOperationAction& nextOperation)
at Microsoft.CodeAnalysis.Formatting.ChainedFormattingRules.AddIndentBlockOperations(List1 list, SyntaxNode currentNode) at Microsoft.CodeAnalysis.Formatting.AbstractFormatEngine.AddOperations[T](SegmentedList1 operations, List1 scratch, SyntaxNode node, Action2 addOperations)
at Microsoft.CodeAnalysis.Formatting.AbstractFormatEngine.CreateNodeOperations(CancellationToken cancellationToken)
at Microsoft.CodeAnalysis.Formatting.AbstractFormatEngine.Format(CancellationToken cancellationToken)
at Microsoft.CodeAnalysis.Formatting.AbstractSyntaxFormatting.GetFormattingResult(SyntaxNode node, IEnumerable1 spans, SyntaxFormattingOptions options, ImmutableArray1 rules, CancellationToken cancellationToken)
at Microsoft.CodeAnalysis.Formatting.Formatter.GetFormattedTextChanges(SyntaxNode node, IEnumerable1 spans, SolutionServices services, SyntaxFormattingOptions options, ImmutableArray1 rules, CancellationToken cancellationToken)
at Microsoft.CodeAnalysis.Formatting.Formatter.GetFormattedTextChanges(SyntaxNode node, TextSpan span, SolutionServices services, SyntaxFormattingOptions options, CancellationToken cancellationToken)
at Microsoft.CodeAnalysis.Razor.Formatting.CSharpFormattingPass.FormatCSharpAsync(SourceText generatedCSharpText, RazorFormattingOptions options, CancellationToken cancellationToken)
at Microsoft.CodeAnalysis.Razor.Formatting.CSharpFormattingPass.ExecuteAsync(FormattingContext context, ImmutableArray1 changes, CancellationToken cancellationToken) at Microsoft.CodeAnalysis.Razor.Formatting.RazorFormattingService.GetDocumentFormattingChangesAsync(DocumentContext documentContext, ImmutableArray1 htmlChanges, Nullable1 range, RazorFormattingOptions options, CancellationToken cancellationToken) at Microsoft.CodeAnalysis.Remote.RemoteWorkspace.<>c__DisplayClass7_01.<g__ProcessSolutionAsync|1>d.MoveNext()
--- End of stack trace from previous location ---
at Microsoft.CodeAnalysis.Remote.RemoteWorkspace.RunWithSolutionAsync[T](AssetProvider assetProvider, Checksum solutionChecksum, Boolean updatePrimaryBranch, Func2 implementation, CancellationToken cancellationToken) at Microsoft.CodeAnalysis.Remote.RemoteWorkspace.RunWithSolutionAsync[T](AssetProvider assetProvider, Checksum solutionChecksum, Boolean updatePrimaryBranch, Func2 implementation, CancellationToken cancellationToken)
at Microsoft.CodeAnalysis.Remote.RemoteWorkspaceManager.RunServiceAsync[T](ServiceBrokerClient client, Checksum solutionChecksum, Func`2 implementation, CancellationToken cancellationToken)

on this file:

@using ThisType = Styling
@using CODie.Blazor.Common;

@if (OnClick.HasDelegate)
{
    <div class=@ClassStr style=@StyleStr data-name=@Name @onclick=OnClick>
        @ChildContent
    </div>
}
else
{
    <div class=@ClassStr style=@StyleStr data-name=@Name>
        @ChildContent
    </div>
}
@code
{
    // additional properties need to be registered in DivStylingInheritance.css
    [Parameter, EditorRequired] public required RenderFragment? ChildContent { get; set; }

    private string ClassStr => $"styling {(DontInherit ? "" : "IsInherited")}{(CssClass is null ? null : $" {CssClass}")}";

    private string StyleStr => $"display:contents; {HeightStr} {WidthStr} {ColorStr} {BackgroundColorStr} {CursorStr} {Style} {ZoomStr} {PaddingStr} {BorderStr}";

    [Parameter] public string? CssClass { get; set; }

    [Parameter] public string? Style { get; set; }

    [Parameter] public string? Cursor { get; set; }
    private string CursorStr => Cursor.GetCssStr();

    [Parameter] public int? Height { get; set; }
    [Parameter] public int? HeightPercent { get; set; }
    private string HeightStr => Height.GetCssStr() ?? HeightPercent.GetCssStrPercent();


    [Parameter] public Colors? Color { get; set; }
    private string ColorStr => Color.GetCssStr(ColorSystem.ColorString);

    [Parameter] public Colors? BackgroundColor { get; set; }
    private string BackgroundColorStr => BackgroundColor.GetCssStr(ColorSystem.ColorString, "background");

    [Parameter] public int? Width { get; set; }
    private string WidthStr => Width.GetCssStr();

    [Parameter] public bool DontInherit { get; set; }

    [Parameter] public EventCallback<MouseEventArgs> OnClick { get; set; }

    [Parameter] public string? Name { get; set; }

    [Parameter] public int? Zoom { get; set; }
    private string ZoomStr => Zoom.GetCssStr();

    [Parameter] public Choice<(int Top, int Right, int Bottom, int Left), (int, int), int>? Padding { get; set; }
    private string PaddingStr => Padding.Do(
        pd => $"padding:{pd.Top}px {pd.Right}px {pd.Bottom}px {pd.Left}px;",
        pd => $"padding:{pd.Top}px {pd.Right}px {pd.Bottom}px {pd.Left}px;",
        pd => $"padding:{pd.Top}px {pd.Right}px {pd.Bottom}px {pd.Left}px;"
        :

    [Parameter] public bool BorderBottom { get; set; }
    [Parameter] public bool BorderRight { get; set; }
    [Parameter] public bool BorderLeft { get; set; }
    [Parameter] public bool BorderTop { get; set; }
    [Parameter] public bool Border { get; set; }
    private string BorderStr => Border
    ? BorderStringCss()
    : $"{(BorderTop ? BorderStringCss(BorderDirections.Top) : "")}{(BorderBottom ? BorderStringCss(BorderDirections.Bottom) : "")}{(BorderLeft ? BorderStringCss(BorderDirections.Left) : "")}{(BorderRight ? BorderStringCss(BorderDirections.Right) : "")}";

    private string BorderStringCss(BorderDirections dir, BorderStyles style = BorderStyles.Solid, int width = 1, Colors color = Colors.BorderPrimaryGrey)
    => $"border-{dir.GetCssValueStr()}:{width}px {style.GetCssValueStr()} {color.GetCssValueStr(ColorSystem.ColorString)};";

    private string BorderStringCss(BorderStyles style = BorderStyles.Solid, int width = 1, Colors color = Colors.BorderPrimaryGrey)
    => $"border:{width}px {style.GetCssValueStr()} {color.GetCssValueStr(ColorSystem.ColorString)};";

}

in line 60 (the selected line in the screenshot

this is syntactically wrong, i know.

removing the colon and doing ctrl-k-c then at least doesn't produce the error bar.

The failure is reported in IndentBlockOperation.cs line 38 and reaches RazorFormattingService through CSharpFormattingPass. Reproduce it with the supplied .razor content, especially line 60's lone colon, using Ctrl-K-Ctrl-D, then trace the formatting operation and verify malformed input no longer produces the exception bar.