{"record":{"id":"e3e492cf70e15c00","repo":"AvaloniaUI/Avalonia","slug":"unexpected-token","errorCode":null,"errorMessage":"Unexpected '{token}'","messagePattern":"Unexpected '(.+?)'","errorType":"exception","errorClass":"ExpressionParseException","httpStatus":null,"severity":"error","filePath":"src/Avalonia.Base/Rendering/Composition/Expressions/ExpressionParser.cs","lineNumber":204,"sourceCode":"                if (_expressions == null)\n                    return _first ?? throw new InvalidOperationException();\n                return ToExpression(0, _expressions.Count - 1);\n            }\n        }\n\n        static Expression ParseTillTerminator(ref TokenParser parser, string terminatorChars, \n            bool throwOnTerminator,\n            bool throwOnEnd,\n            out char? token)\n        {\n            ExpressionOperatorGroup left = default;\n            token = null;\n            while (true)\n            {\n                if (parser.TryConsumeAny(terminatorChars.AsSpan(), out var consumedToken))\n                {\n                    if (throwOnTerminator || left.Empty)\n                        throw new ExpressionParseException($\"Unexpected '{token}'\", parser.Position - 1);\n                    token = consumedToken;\n                    return left.ToExpression();\n                }\n                parser.SkipWhitespace();\n                if (parser.Length == 0)\n                {\n                    if (throwOnEnd || left.Empty)\n                        throw new ExpressionParseException(\"Unexpected end of  expression\", parser.Position);\n                    return left.ToExpression();\n                }\n                \n                ExpressionType? op = null;\n                if (left.NotEmpty)\n                {\n                    if (parser.TryConsume('?'))\n                    {\n                        var truePart = ParseTillTerminator(ref parser, \":\",\n                            false, true, out _);","sourceCodeStart":186,"sourceCodeEnd":222,"githubUrl":"https://github.com/AvaloniaUI/Avalonia/blob/11c542726898ae954a1ef668c65ec79ec92ab17d/src/Avalonia.Base/Rendering/Composition/Expressions/ExpressionParser.cs#L186-L222","documentation":"Error \"Unexpected '{token}'\" thrown in AvaloniaUI/Avalonia.","triggerScenarios":"Raised when the composition expression tokenizer encounters a token that is not valid at the current parse position. Defend by checking expression syntax (identifiers, operators, parentheses) before use and by guarding against malformed input strings.","commonSituations":"See trigger scenarios.","solutions":["Correct the expression string so the reported token is valid in that position; check for typos in property names, operators, or function calls.","Quote string literals and ensure identifiers match existing animatable property names on the target visual."],"exampleFix":null,"handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"11c542726898ae954a1ef668c65ec79ec92ab17d","analyzedAt":"2026-08-13T11:57:40.261Z","schemaVersion":2},"datasetVersion":"2026-08-13T14:17:21.547Z"}