diff --git a/pkg/analysis_server/lib/src/lsp/handlers/handler_code_actions.dart b/pkg/analysis_server/lib/src/lsp/handlers/handler_code_actions.dart
index c55a22e..35bc6e9 100644
--- a/pkg/analysis_server/lib/src/lsp/handlers/handler_code_actions.dart
+++ b/pkg/analysis_server/lib/src/lsp/handlers/handler_code_actions.dart
@@ -34,6 +34,10 @@
 
   Future<ErrorOr<List<Either2<Command, CodeAction>>>> handle(
       CodeActionParams params) async {
+    if (!isDartDocument(params.textDocument)) {
+      return success(const []);
+    }
+
     final capabilities = server?.clientCapabilities?.textDocument?.codeAction;
 
     final clientSupportsLiteralCodeActions =
diff --git a/pkg/analysis_server/lib/src/lsp/handlers/handler_completion.dart b/pkg/analysis_server/lib/src/lsp/handlers/handler_completion.dart
index 67a3fa8..147b48f 100644
--- a/pkg/analysis_server/lib/src/lsp/handlers/handler_completion.dart
+++ b/pkg/analysis_server/lib/src/lsp/handlers/handler_completion.dart
@@ -49,6 +49,10 @@
       CompletionParams.jsonHandler;
 
   Future<ErrorOr<List<CompletionItem>>> handle(CompletionParams params) async {
+    if (!isDartDocument(params.textDocument)) {
+      return success(const []);
+    }
+
     final completionCapabilities =
         server?.clientCapabilities?.textDocument?.completion;
 
diff --git a/pkg/analysis_server/lib/src/lsp/handlers/handler_definition.dart b/pkg/analysis_server/lib/src/lsp/handlers/handler_definition.dart
index 51f7b2f..ead355a 100644
--- a/pkg/analysis_server/lib/src/lsp/handlers/handler_definition.dart
+++ b/pkg/analysis_server/lib/src/lsp/handlers/handler_definition.dart
@@ -24,6 +24,10 @@
 
   Future<ErrorOr<List<Location>>> handle(
       TextDocumentPositionParams params) async {
+    if (!isDartDocument(params.textDocument)) {
+      return success(const []);
+    }
+
     final pos = params.position;
     final path = pathOfDoc(params.textDocument);
     final unit = await path.mapResult(requireResolvedUnit);
diff --git a/pkg/analysis_server/lib/src/lsp/handlers/handler_document_highlights.dart b/pkg/analysis_server/lib/src/lsp/handlers/handler_document_highlights.dart
index c2fabbd..5be52b6 100644
--- a/pkg/analysis_server/lib/src/lsp/handlers/handler_document_highlights.dart
+++ b/pkg/analysis_server/lib/src/lsp/handlers/handler_document_highlights.dart
@@ -23,6 +23,10 @@
 
   Future<ErrorOr<List<DocumentHighlight>>> handle(
       TextDocumentPositionParams params) async {
+    if (!isDartDocument(params.textDocument)) {
+      return success(const []);
+    }
+
     final pos = params.position;
     final path = pathOfDoc(params.textDocument);
     final unit = await path.mapResult(requireResolvedUnit);
diff --git a/pkg/analysis_server/lib/src/lsp/handlers/handler_document_symbols.dart b/pkg/analysis_server/lib/src/lsp/handlers/handler_document_symbols.dart
index 6c5b120..a4c623b 100644
--- a/pkg/analysis_server/lib/src/lsp/handlers/handler_document_symbols.dart
+++ b/pkg/analysis_server/lib/src/lsp/handlers/handler_document_symbols.dart
@@ -49,6 +49,12 @@
 
   Future<ErrorOr<Either2<List<DocumentSymbol>, List<SymbolInformation>>>>
       handle(DocumentSymbolParams params) async {
+    if (!isDartDocument(params.textDocument)) {
+      return success(
+        Either2<List<DocumentSymbol>, List<SymbolInformation>>.t2([]),
+      );
+    }
+
     final symbolCapabilities =
         server?.clientCapabilities?.textDocument?.documentSymbol;
 
diff --git a/pkg/analysis_server/lib/src/lsp/handlers/handler_folding.dart b/pkg/analysis_server/lib/src/lsp/handlers/handler_folding.dart
index 50d8ca3..7ad848d 100644
--- a/pkg/analysis_server/lib/src/lsp/handlers/handler_folding.dart
+++ b/pkg/analysis_server/lib/src/lsp/handlers/handler_folding.dart
@@ -21,6 +21,10 @@
       FoldingRangeParams.jsonHandler;
 
   Future<ErrorOr<List<FoldingRange>>> handle(FoldingRangeParams params) async {
+    if (!isDartDocument(params.textDocument)) {
+      return success(const []);
+    }
+
     final path = pathOfDoc(params.textDocument);
     final unit = await path.mapResult(requireUnresolvedUnit);
 
diff --git a/pkg/analysis_server/lib/src/lsp/handlers/handler_hover.dart b/pkg/analysis_server/lib/src/lsp/handlers/handler_hover.dart
index 7d0db4f..6e2ee05 100644
--- a/pkg/analysis_server/lib/src/lsp/handlers/handler_hover.dart
+++ b/pkg/analysis_server/lib/src/lsp/handlers/handler_hover.dart
@@ -25,6 +25,10 @@
       TextDocumentPositionParams.jsonHandler;
 
   Future<ErrorOr<Hover>> handle(TextDocumentPositionParams params) async {
+    if (!isDartDocument(params.textDocument)) {
+      return success(null);
+    }
+
     final pos = params.position;
     final path = pathOfDoc(params.textDocument);
     final unit = await path.mapResult(requireResolvedUnit);
diff --git a/pkg/analysis_server/lib/src/lsp/handlers/handler_references.dart b/pkg/analysis_server/lib/src/lsp/handlers/handler_references.dart
index c025819..f410e9f 100644
--- a/pkg/analysis_server/lib/src/lsp/handlers/handler_references.dart
+++ b/pkg/analysis_server/lib/src/lsp/handlers/handler_references.dart
@@ -29,6 +29,10 @@
 
   @override
   Future<ErrorOr<List<Location>>> handle(ReferenceParams params) async {
+    if (!isDartDocument(params.textDocument)) {
+      return success(const []);
+    }
+
     final pos = params.position;
     final path = pathOfDoc(params.textDocument);
     final unit = await path.mapResult(requireResolvedUnit);
diff --git a/pkg/analysis_server/lib/src/lsp/handlers/handler_signature_help.dart b/pkg/analysis_server/lib/src/lsp/handlers/handler_signature_help.dart
index 7fa60a7..90ef021 100644
--- a/pkg/analysis_server/lib/src/lsp/handlers/handler_signature_help.dart
+++ b/pkg/analysis_server/lib/src/lsp/handlers/handler_signature_help.dart
@@ -23,6 +23,10 @@
 
   Future<ErrorOr<SignatureHelp>> handle(
       TextDocumentPositionParams params) async {
+    if (!isDartDocument(params.textDocument)) {
+      return success(null);
+    }
+
     final pos = params.position;
     final path = pathOfDoc(params.textDocument);
     final unit = await path.mapResult(requireResolvedUnit);
diff --git a/pkg/analysis_server/lib/src/lsp/mapping.dart b/pkg/analysis_server/lib/src/lsp/mapping.dart
index 2f9dd65..53715b7 100644
--- a/pkg/analysis_server/lib/src/lsp/mapping.dart
+++ b/pkg/analysis_server/lib/src/lsp/mapping.dart
@@ -267,6 +267,9 @@
   }
 }
 
+bool isDartDocument(lsp.TextDocumentIdentifier doc) =>
+    doc?.uri?.endsWith('.dart');
+
 lsp.Location navigationTargetToLocation(String targetFilePath,
     server.NavigationTarget target, server.LineInfo lineInfo) {
   if (lineInfo == null) {
diff --git a/pkg/analysis_server/test/lsp/code_actions_assists_test.dart b/pkg/analysis_server/test/lsp/code_actions_assists_test.dart
index a42d083..7c37bec 100644
--- a/pkg/analysis_server/test/lsp/code_actions_assists_test.dart
+++ b/pkg/analysis_server/test/lsp/code_actions_assists_test.dart
@@ -91,4 +91,16 @@
     applyChanges(contents, assistAction.edit.changes);
     expect(contents[mainFilePath], equals(expectedContent));
   }
+
+  test_nonDartFile() async {
+    await newFile(pubspecFilePath, content: simplePubspecContent);
+    await initialize(
+      textDocumentCapabilities: withCodeActionKinds(
+          emptyTextDocumentClientCapabilities, [CodeActionKind.Refactor]),
+    );
+
+    final codeActions =
+        await getCodeActions(pubspecFileUri.toString(), range: startOfDocRange);
+    expect(codeActions, isEmpty);
+  }
 }
diff --git a/pkg/analysis_server/test/lsp/code_actions_fixes_test.dart b/pkg/analysis_server/test/lsp/code_actions_fixes_test.dart
index 4d692a1..daadf31 100644
--- a/pkg/analysis_server/test/lsp/code_actions_fixes_test.dart
+++ b/pkg/analysis_server/test/lsp/code_actions_fixes_test.dart
@@ -93,4 +93,16 @@
     applyChanges(contents, fixAction.edit.changes);
     expect(contents[mainFilePath], equals(expectedContent));
   }
+
+  test_nonDartFile() async {
+    await newFile(pubspecFilePath, content: simplePubspecContent);
+    await initialize(
+      textDocumentCapabilities: withCodeActionKinds(
+          emptyTextDocumentClientCapabilities, [CodeActionKind.QuickFix]),
+    );
+
+    final codeActions =
+        await getCodeActions(pubspecFileUri.toString(), range: startOfDocRange);
+    expect(codeActions, isEmpty);
+  }
 }
diff --git a/pkg/analysis_server/test/lsp/code_actions_source_test.dart b/pkg/analysis_server/test/lsp/code_actions_source_test.dart
index 3ea0d20..a2ead0f 100644
--- a/pkg/analysis_server/test/lsp/code_actions_source_test.dart
+++ b/pkg/analysis_server/test/lsp/code_actions_source_test.dart
@@ -406,6 +406,18 @@
         throwsA(isResponseError(ServerErrorCodes.FileHasErrors)));
   }
 
+  test_nonDartFile() async {
+    await newFile(pubspecFilePath, content: simplePubspecContent);
+    await initialize(
+      textDocumentCapabilities: withCodeActionKinds(
+          emptyTextDocumentClientCapabilities, [CodeActionKind.Source]),
+    );
+
+    final codeActions =
+        await getCodeActions(pubspecFileUri.toString(), range: startOfDocRange);
+    expect(codeActions, isEmpty);
+  }
+
   test_unavailableWhenNotRequested() async {
     await newFile(mainFilePath);
     await initialize(
diff --git a/pkg/analysis_server/test/lsp/completion_test.dart b/pkg/analysis_server/test/lsp/completion_test.dart
index b3554c1..f45fe3c 100644
--- a/pkg/analysis_server/test/lsp/completion_test.dart
+++ b/pkg/analysis_server/test/lsp/completion_test.dart
@@ -192,6 +192,14 @@
     expect(item.detail, isNot(contains('deprecated')));
   }
 
+  test_nonDartFile() async {
+    newFile(pubspecFilePath, content: simplePubspecContent);
+    await initialize();
+
+    final res = await getCompletion(pubspecFileUri, startOfDocPos);
+    expect(res, isEmpty);
+  }
+
   test_plainText() async {
     final content = '''
     class MyClass {
diff --git a/pkg/analysis_server/test/lsp/definition_test.dart b/pkg/analysis_server/test/lsp/definition_test.dart
index 4e99a7f..a7df3fe 100644
--- a/pkg/analysis_server/test/lsp/definition_test.dart
+++ b/pkg/analysis_server/test/lsp/definition_test.dart
@@ -53,6 +53,14 @@
     expect(loc.uri, equals(referencedFileUri.toString()));
   }
 
+  test_nonDartFile() async {
+    newFile(pubspecFilePath, content: simplePubspecContent);
+    await initialize();
+
+    final res = await getDefinition(pubspecFileUri, startOfDocPos);
+    expect(res, isEmpty);
+  }
+
   test_singleFile() async {
     final contents = '''
     [[foo]]() {
diff --git a/pkg/analysis_server/test/lsp/document_highlights_test.dart b/pkg/analysis_server/test/lsp/document_highlights_test.dart
index 7f002b4..374dd1d 100644
--- a/pkg/analysis_server/test/lsp/document_highlights_test.dart
+++ b/pkg/analysis_server/test/lsp/document_highlights_test.dart
@@ -29,6 +29,17 @@
     }
     ''');
 
+  test_nonDartFile() async {
+    await initialize();
+    await openFile(pubspecFileUri, simplePubspecContent);
+
+    final highlights =
+        await getDocumentHighlights(pubspecFileUri, startOfDocPos);
+
+    // Non-Dart files should return empty results, not errors.
+    expect(highlights, isEmpty);
+  }
+
   test_noResult() => _testMarkedContent('''
     main() {
       // This one is in a ^ comment!
diff --git a/pkg/analysis_server/test/lsp/document_symbols_test.dart b/pkg/analysis_server/test/lsp/document_symbols_test.dart
index b29ec7e..6d56201 100644
--- a/pkg/analysis_server/test/lsp/document_symbols_test.dart
+++ b/pkg/analysis_server/test/lsp/document_symbols_test.dart
@@ -104,4 +104,16 @@
     expect(method.kind, equals(SymbolKind.Method));
     expect(method.containerName, equals(myClass.name));
   }
+
+  test_nonDartFile() async {
+    newFile(pubspecFilePath, content: simplePubspecContent);
+    await initialize();
+
+    final result = await getDocumentSymbols(pubspecFileUri.toString());
+    final symbols = result.map(
+      (docsymbols) => throw 'Expected SymbolInformations, got DocumentSymbols',
+      (symbolInfos) => symbolInfos,
+    );
+    expect(symbols, isEmpty);
+  }
 }
diff --git a/pkg/analysis_server/test/lsp/folding_test.dart b/pkg/analysis_server/test/lsp/folding_test.dart
index 0b41612..098010c 100644
--- a/pkg/analysis_server/test/lsp/folding_test.dart
+++ b/pkg/analysis_server/test/lsp/folding_test.dart
@@ -66,6 +66,14 @@
     expect(regions, unorderedEquals(expectedRegions));
   }
 
+  test_nonDartFile() async {
+    await initialize();
+    await openFile(pubspecFileUri, simplePubspecContent);
+
+    final regions = await getFoldingRegions(pubspecFileUri);
+    expect(regions, isEmpty);
+  }
+
   test_headersImportsComments() async {
     // TODO(dantup): Review why the file header and the method comment ranges
     // are different... one spans only the range to collapse, but the other
diff --git a/pkg/analysis_server/test/lsp/format_test.dart b/pkg/analysis_server/test/lsp/format_test.dart
index 17a34b0..52d944e 100644
--- a/pkg/analysis_server/test/lsp/format_test.dart
+++ b/pkg/analysis_server/test/lsp/format_test.dart
@@ -63,6 +63,15 @@
     expect(formatEdits, isNull);
   }
 
+  test_nonDartFile() async {
+    await initialize();
+    await openFile(pubspecFileUri, simplePubspecContent);
+
+    final formatEdits =
+        await formatOnType(pubspecFileUri.toString(), startOfDocPos, '}');
+    expect(formatEdits, isNull);
+  }
+
   test_path_doesNotExist() async {
     await initialize();
 
diff --git a/pkg/analysis_server/test/lsp/hover_test.dart b/pkg/analysis_server/test/lsp/hover_test.dart
index f1312e2..fa3e520 100644
--- a/pkg/analysis_server/test/lsp/hover_test.dart
+++ b/pkg/analysis_server/test/lsp/hover_test.dart
@@ -107,6 +107,13 @@
     expect(hover, isNull);
   }
 
+  test_nonDartFile() async {
+    await initialize();
+    await openFile(pubspecFileUri, simplePubspecContent);
+    final hover = await getHover(pubspecFileUri, startOfDocPos);
+    expect(hover, isNull);
+  }
+
   test_plainText_simple() async {
     final content = '''
     /// This is a string.
diff --git a/pkg/analysis_server/test/lsp/references_test.dart b/pkg/analysis_server/test/lsp/references_test.dart
index bd36c11..0c69bca 100644
--- a/pkg/analysis_server/test/lsp/references_test.dart
+++ b/pkg/analysis_server/test/lsp/references_test.dart
@@ -99,6 +99,14 @@
     expect(loc.uri, equals(mainFileUri.toString()));
   }
 
+  test_nonDartFile() async {
+    newFile(pubspecFilePath, content: simplePubspecContent);
+    await initialize();
+
+    final res = await getReferences(pubspecFileUri, startOfDocPos);
+    expect(res, isEmpty);
+  }
+
   test_singleFile_withoutDeclaration() async {
     final contents = '''
     f^oo() {
diff --git a/pkg/analysis_server/test/lsp/server_abstract.dart b/pkg/analysis_server/test/lsp/server_abstract.dart
index 108a850..3b3c826 100644
--- a/pkg/analysis_server/test/lsp/server_abstract.dart
+++ b/pkg/analysis_server/test/lsp/server_abstract.dart
@@ -40,8 +40,11 @@
       new RegExp(allMarkers.map(RegExp.escape).join('|'));
 
   int _id = 0;
-  String projectFolderPath, mainFilePath;
-  Uri projectFolderUri, mainFileUri;
+  String projectFolderPath, mainFilePath, pubspecFilePath;
+  Uri projectFolderUri, mainFileUri, pubspecFileUri;
+  final String simplePubspecContent = 'name: my_project';
+  final startOfDocPos = new Position(0, 0);
+  final startOfDocRange = new Range(new Position(0, 0), new Position(0, 0));
 
   Stream<Message> get serverToClient;
 
@@ -786,6 +789,8 @@
     newFile(join(projectFolderPath, 'lib', 'file.dart'));
     mainFilePath = join(projectFolderPath, 'lib', 'main.dart');
     mainFileUri = Uri.file(mainFilePath);
+    pubspecFilePath = join(projectFolderPath, 'pubspec.yaml');
+    pubspecFileUri = Uri.file(pubspecFilePath);
   }
 
   Future tearDown() async {
diff --git a/pkg/analysis_server/test/lsp/signature_help_test.dart b/pkg/analysis_server/test/lsp/signature_help_test.dart
index e22eec0..4471683 100644
--- a/pkg/analysis_server/test/lsp/signature_help_test.dart
+++ b/pkg/analysis_server/test/lsp/signature_help_test.dart
@@ -122,6 +122,15 @@
     );
   }
 
+  test_nonDartFile() async {
+    await initialize(
+        textDocumentCapabilities: withSignatureHelpContentFormat(
+            emptyTextDocumentClientCapabilities, [MarkupKind.PlainText]));
+    await openFile(pubspecFileUri, simplePubspecContent);
+    final res = await getSignatureHelp(pubspecFileUri, startOfDocPos);
+    expect(res, isNull);
+  }
+
   test_params_multipleNamed() async {
     final content = '''
     /// Does foo.