https://forge.codesys.com/forge/talk/Engineering/thread/a3f4f40596/Recent posts to Codesys v3.5.22.10 - Internal error:System.AggregateException...Value cannot be null...Parameter name: expLValueenWed, 22 Apr 2026 08:28:39 -0000https://forge.codesys.com/forge/talk/Engineering/thread/a3f4f40596/?limit=25#8081<div class="markdown_content"><p>Hi to all,</p> <p>I receive an error when I try to compile a project that in v.3.5.21.50 have no problem.</p> <p>The error seems to comes out when I add the Visualization part into the project.</p> <p>The complete error is:</p> <p><span>[ERROR]</span> Internal error:System.AggregateException: One or more errors occurred. ---&gt; System.Exception: Internal error in Code ---&gt; System.ArgumentNullException: Value cannot be null. Parameter name: expLValue at _3S.CoDeSys.LanguageModelManager.LanguageModelBuilder.CreateAssignmentExpression(IExprementPosition pos, IExpression expLValue, IExpression expRValue, Operator kindof) at _3S.CoDeSys.LanguageModelManager.LanguageModelBuilder.CreateAssignmentStatement(IExprementPosition pos, IExpression expLeft, IExpression expRight) at ..
(IExpression , IExpression ) at ..
(_IAssignmentExpression ,  ) at _3S.CoDeSys.Compiler35220.Phase5_Codegeneration.Optimization.AssignmentStatementReplacer.ReplaceExpressionStatement(_IExpressionStatement expressionStatement, _ICompiledPOU cpou) at _3S.CoDeSys.Compiler35220.Phase5_Codegeneration.Optimization.ExpressionStatementReplacerVisitor.visit(_ISequenceStatement sequenceStatement) at _3S.CoDeSys.Compiler35220.Phase5_Codegeneration.Optimization.ExpressionStatementReplacerVisitor.visit(_IIfStatement ifst) at _3S.CoDeSys.Compiler35220.Phase5_Codegeneration.Optimization.ExpressionStatementReplacerVisitor.visit(_ISequenceStatement sequenceStatement) at _3S.CoDeSys.Compiler35220.Phase5_Codegeneration.Optimization.ExpressionStatementReplacerVisitor.visit(_IIfStatement ifst) at _3S.CoDeSys.Compiler35220.Phase5_Codegeneration.Optimization.ExpressionStatementReplacerVisitor.visit(_ISequenceStatement sequenceStatement) at _3S.CoDeSys.Compiler35220.Phase5_Codegeneration.Optimization.ExpressionStatementReplacerVisitor.visit(_IForStatement forloop) at _3S.CoDeSys.Compiler35220.Phase5_Codegeneration.Optimization.ExpressionStatementReplacerVisitor.visit(_ISequenceStatement sequenceStatement) at _3S.CoDeSys.Compiler35220.Phase5_Codegeneration.Optimization.ExpressionStatementReplacerVisitor.visit(_ISequenceStatement sequenceStatement) at ..
(_ICompiledPOU ) at ..(_ICompiledPOU ) at _3S.CoDeSys.Compiler35220.Phase5_Codegeneration.Codegeneration.
(_ICompiledPOU , _ISignature ) at ..
(_ICompiledPOU ) at ..
(_ICompiledPOU&amp; ) at ..
() --- End of inner exception stack trace --- --- End of inner exception stack trace --- at _3S.CoDeSys.Compiler35220.CompilerPhases.CompilerPhase5_Codegenerator.
(IList<code>1 ) at _3S.CoDeSys.Compiler35220.CompilerPhases.CompilerPhase5_Codegenerator.
(IScope5 , IList</code>1 ) at _3S.CoDeSys.Compiler35220.CompilerPhases.CompilerPhase5_Codegenerator.
(ICodegenerator ) at _3S.CoDeSys.Compiler35220.CompilerPhases.CompilerPhaseControllerGenerateCode.() at _3S.CoDeSys.Compiler35220.CompilerPhases.CompilerPhaseControllerGenerateCode.() ---&gt; (Inner Exception #0) System.Exception: Internal error in Code ---&gt; System.ArgumentNullException: Value cannot be null. Parameter name: expLValue at _3S.CoDeSys.LanguageModelManager.LanguageModelBuilder.CreateAssignmentExpression(IExprementPosition pos, IExpression expLValue, IExpression expRValue, Operator kindof) at _3S.CoDeSys.LanguageModelManager.LanguageModelBuilder.CreateAssignmentStatement(IExprementPosition pos, IExpression expLeft, IExpression expRight) at ..
(IExpression , IExpression ) at ..
(_IAssignmentExpression ,  ) at _3S.CoDeSys.Compiler35220.Phase5_Codegeneration.Optimization.AssignmentStatementReplacer.ReplaceExpressionStatement(_IExpressionStatement expressionStatement, _ICompiledPOU cpou) at _3S.CoDeSys.Compiler35220.Phase5_Codegeneration.Optimization.ExpressionStatementReplacerVisitor.visit(_ISequenceStatement sequenceStatement) at _3S.CoDeSys.Compiler35220.Phase5_Codegeneration.Optimization.ExpressionStatementReplacerVisitor.visit(_IIfStatement ifst) at _3S.CoDeSys.Compiler35220.Phase5_Codegeneration.Optimization.ExpressionStatementReplacerVisitor.visit(_ISequenceStatement sequenceStatement) at _3S.CoDeSys.Compiler35220.Phase5_Codegeneration.Optimization.ExpressionStatementReplacerVisitor.visit(_IIfStatement ifst) at _3S.CoDeSys.Compiler35220.Phase5_Codegeneration.Optimization.ExpressionStatementReplacerVisitor.visit(_ISequenceStatement sequenceStatement) at _3S.CoDeSys.Compiler35220.Phase5_Codegeneration.Optimization.ExpressionStatementReplacerVisitor.visit(_IForStatement forloop) at _3S.CoDeSys.Compiler35220.Phase5_Codegeneration.Optimization.ExpressionStatementReplacerVisitor.visit(_ISequenceStatement sequenceStatement) at _3S.CoDeSys.Compiler35220.Phase5_Codegeneration.Optimization.ExpressionStatementReplacerVisitor.visit(_ISequenceStatement sequenceStatement) at ..
(_ICompiledPOU ) at ..(_ICompiledPOU ) at _3S.CoDeSys.Compiler35220.Phase5_Codegeneration.Codegeneration.
(_ICompiledPOU , _ISignature ) at ..
(_ICompiledPOU ) at ..
(_ICompiledPOU&amp; ) at ..
() --- End of inner exception stack trace ---&lt;--- </p></div>vstromWed, 22 Apr 2026 08:28:39 -0000https://forge.codesys.com727f7c93bb471adee67fda3d35fef6d88d22f031