diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/TagHelperBlockRewriter.cs b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/TagHelperBlockRewriter.cs
index ebf32e9f70..a585b8781b 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/TagHelperBlockRewriter.cs
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/TagHelperBlockRewriter.cs
@@ -480,6 +480,28 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
                 return base.VisitRazorMetaCode(node);
             }
 
+            public override SyntaxNode VisitCSharpStatement(CSharpStatementSyntax node)
+            {
+                // We don't support code blocks inside tag helper attributes. Don't rewrite anything inside a code block.
+                // E.g, <p age="@{1 + 2}"> is not supported.
+                return node;
+            }
+
+            public override SyntaxNode VisitRazorDirective(RazorDirectiveSyntax node)
+            {
+                // We don't support directives inside tag helper attributes. Don't rewrite anything inside a directive.
+                // E.g, <p age="@functions { }"> is not supported.
+                return node;
+            }
+
+            public override SyntaxNode VisitMarkupElement(MarkupElementSyntax node)
+            {
+                // We're visiting an attribute value. If we encounter a MarkupElement this means the attribute value is invalid.
+                // We don't want to rewrite anything here.
+                // E.g, <my age="@if (true) { <my4 age=... }"></my4>
+                return node;
+            }
+
             public override SyntaxNode VisitCSharpExpressionLiteral(CSharpExpressionLiteralSyntax node)
             {
                 if (!_tryParseResult.IsBoundNonStringAttribute)
diff --git a/src/Razor/test/Microsoft.AspNetCore.Razor.Test.Common/Language/IntegrationTests/IntegrationTestBase.cs b/src/Razor/test/Microsoft.AspNetCore.Razor.Test.Common/Language/IntegrationTests/IntegrationTestBase.cs
index 11818a68dc..61890d8f61 100644
--- a/src/Razor/test/Microsoft.AspNetCore.Razor.Test.Common/Language/IntegrationTests/IntegrationTestBase.cs
+++ b/src/Razor/test/Microsoft.AspNetCore.Razor.Test.Common/Language/IntegrationTests/IntegrationTestBase.cs
@@ -409,7 +409,7 @@ namespace Microsoft.AspNetCore.Razor.Language.IntegrationTests
                 baselineDiagnostics = diagnosticsFile.ReadAllText();
             }
 
-            var actualDiagnostics = string.Concat(cSharpDocument.Diagnostics.Select(d => RazorDiagnosticSerializer.Serialize(d) + "\r\n"));
+            var actualDiagnostics = string.Concat(cSharpDocument.Diagnostics.Select(d => NormalizeNewLines(RazorDiagnosticSerializer.Serialize(d)) + "\r\n"));
             Assert.Equal(baselineDiagnostics, actualDiagnostics);
         }
 
@@ -541,6 +541,30 @@ namespace Microsoft.AspNetCore.Razor.Language.IntegrationTests
                 }
                 return base.VisitCSharpExpressionLiteral(node);
             }
+
+            public override Syntax.SyntaxNode VisitCSharpStatement(CSharpStatementSyntax node)
+            {
+                if (node.FirstAncestorOrSelf<MarkupTagHelperAttributeValueSyntax>() != null)
+                {
+                    // We don't support code blocks inside tag helper attribute values.
+                    // If it exists, we don't want to track its code spans for source mappings.
+                    return node;
+                }
+
+                return base.VisitCSharpStatement(node);
+            }
+
+            public override Syntax.SyntaxNode VisitRazorDirective(RazorDirectiveSyntax node)
+            {
+                if (node.FirstAncestorOrSelf<MarkupTagHelperAttributeValueSyntax>() != null)
+                {
+                    // We don't support Razor directives inside tag helper attribute values.
+                    // If it exists, we don't want to track its code spans for source mappings.
+                    return node;
+                }
+
+                return base.VisitRazorDirective(node);
+            }
         }
 
         private static string EscapeWhitespace(string content)