unoplatform/uno · error · Exception

Missing parenthesis?

Error message

Missing parenthesis?

What it means

Thrown by the x:Bind path parser (ParseXBindPath) when an opening '(' is consumed for a parenthesized expression or cast, but the matching ')' is not found after parsing the inner expression. The parser advances past '(', recursively parses a sub-path, then expects ')' as the terminator.

Source

Thrown at src/SourceGenerators/Uno.UI.SourceGenerators/XamlGenerator/Utils/XBindExpressionParser.CoreParser.cs:157

		private void SkipWhitespaces()
		{
			while (char.IsWhiteSpace(Current))
			{
				_position++;
			}
		}

		private XBindPath ParseXBindPath()
		{
			XBindPath path;
			if (Current == '(')
			{
				_position++;
				var expression = ParseXBindPath();
				if (Current != ')')
				{
					throw new Exception("Missing parenthesis?");
				}

				_position++;

				if (char.IsLetter(Current))
				{
					var expression2 = ParseXBindPath();
					return new XBindCast() { Expression = expression2, Type = expression };
				}

				var isPathlessCast = Current != '.' && Current != '[';
				path = new XBindParenthesizedExpression() { Expression = expression, IsPathlessCast = isPathlessCast };
			}
			else
			{
				path = ParseXBindIdentifier();
			}

View on GitHub (pinned to 0418340488)

Solutions

1. Locate the x:Bind expression reported in the build error and inspect every '(' — ensure each has a matching ')'.
2. If using cast syntax {x:Bind (Type)Member}, verify the full pattern '(Type)Member' is present.
3. Remove any stray '(' that was not intended as a cast or grouping.

Example fix

<!-- before -->
<Text Text="{x:Bind (MyConvert ActualText}" />
<!-- after -->
<Text Text="{x:Bind (MyConvert)ActualText}" />

// Before building, validate x:Bind expressions have balanced parens:
// In a pre-build XAML linting step or editor, check:
//   - Every '(' in an x:Bind path has a matching ')'
//   - Cast syntax follows '(Type)Member' exactly
// Most IDEs with XAML language services flag unbalanced parens at edit time.

When it happens

Trigger: An x:Bind expression contains an unmatched '(' — e.g. {x:Bind (MyType)Field} is valid, but a malformed binding like {x:Bind (MyType Field} (missing close paren) or a truncation in the binding path triggers this.

Common situations: Typo in a cast or parenthesized x:Bind expression; copy-paste of a C# cast expression into x:Bind without the closing parenthesis; binding path truncated by an XAML editor or merge tool.

Related errors

• Expected attached property path to be member access.
• Expected ')' in attached property syntax.
• Invalid identifier character {Current}
• x:Bind indexing expects a single literal argument
• Only properties and fields can be indexed.

AI-assisted analysis of unoplatform/uno@0418340488 (2026-08-13). Data as JSON: /api/errors/69fdf1506b5b97f7. Report an issue: GitHub.