diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/DefaultDirectiveSyntaxTreePass.cs b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/DefaultDirectiveSyntaxTreePass.cs
index 8455c9e197..7f567b1109 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/DefaultDirectiveSyntaxTreePass.cs
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/DefaultDirectiveSyntaxTreePass.cs
@@ -65,15 +65,23 @@ namespace Microsoft.AspNetCore.Razor.Language
 
             public override SyntaxNode VisitRazorDirective(RazorDirectiveSyntax node)
             {
-                if (_nestedLevel > 0)
+                if (node.DirectiveDescriptor?.Directive != SectionDirective.Directive.Directive)
+                {
+                    // We only want to track the nesting of section directives.
+                    return base.VisitRazorDirective(node);
+                }
+
+                _nestedLevel++;
+                var result = (RazorDirectiveSyntax)base.VisitRazorDirective(node);
+
+                if (_nestedLevel > 1)
                 {
                     var directiveStart = node.Transition.GetSourceLocation(_syntaxTree.Source);
                     var errorLength = /* @ */ 1 + SectionDirective.Directive.Directive.Length;
                     var error = RazorDiagnosticFactory.CreateParsing_SectionsCannotBeNested(new SourceSpan(directiveStart, errorLength));
-                    node = node.AppendDiagnostic(error);
+                    result = result.AppendDiagnostic(error);
                 }
-                _nestedLevel++;
-                var result = base.VisitRazorDirective(node);
+
                 _nestedLevel--;
 
                 return result;
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/CSharpCodeParser.cs b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/CSharpCodeParser.cs
index 2abfa4ff27..b9dc3bc9d2 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/CSharpCodeParser.cs
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/CSharpCodeParser.cs
@@ -2179,6 +2179,9 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
             CompleteBlock();
             var keyword = OutputAsMetaCode(Output());
             var directiveBody = SyntaxFactory.RazorDirectiveBody(keyword, cSharpCode: null);
+
+            // transition could be null if we're already inside a code block.
+            transition = transition ?? SyntaxFactory.CSharpTransition(SyntaxFactory.MissingToken(SyntaxKind.Transition));
             var directive = SyntaxFactory.RazorDirective(transition, directiveBody);
             builder.Add(directive);
         }
diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/HtmlMarkupParser.cs b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/HtmlMarkupParser.cs
index 02c7eec22d..e66b9c531c 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/HtmlMarkupParser.cs
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/Legacy/HtmlMarkupParser.cs
@@ -1357,8 +1357,6 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
                 var tagStart = CurrentStart;
                 builder.Add(OutputAsMarkupLiteral());
 
-                SpanContext.EditHandler.AcceptedCharacters = endTagAcceptedCharacters;
-
                 var openAngleToken = EatCurrentToken(); // '<'
                 var forwardSlashToken = EatCurrentToken(); // '/'
                 var tagNameToken = EatCurrentToken(); // 'script'
@@ -1369,8 +1367,10 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
                 {
                     var miscAttributeBuilder = pooledResult.Builder;
 
-                    ParseMarkupNodes(miscAttributeBuilder, ParseMode.Text, token => token.Kind == SyntaxKind.CloseAngle);
+                    // We want to accept malformed end tags as content.
+                    AcceptUntil(SyntaxKind.CloseAngle, SyntaxKind.OpenAngle);
                     miscAttributeBuilder.Add(OutputAsMarkupLiteral());
+
                     if (miscAttributeBuilder.Count > 0)
                     {
                         miscContent = SyntaxFactory.MarkupMiscAttributeContent(miscAttributeBuilder.ToList());
@@ -1390,6 +1390,8 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
                     }
                 }
 
+                SpanContext.EditHandler.AcceptedCharacters = endTagAcceptedCharacters;
+
                 endTag = SyntaxFactory.MarkupEndTag(
                     openAngleToken,
                     forwardSlashToken,
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)