diff --git a/Extension/src/Debugger/extension.ts b/Extension/src/Debugger/extension.ts
index 780fa121b..64a62c401 100644
--- a/Extension/src/Debugger/extension.ts
+++ b/Extension/src/Debugger/extension.ts
@@ -14,9 +14,10 @@ import { SshTargetsProvider, getActiveSshTarget, initializeSshTargets, selectSsh
 import { TargetLeafNode, setActiveSshTarget } from '../SSH/TargetsView/targetNodes';
 import { sshCommandToConfig } from '../SSH/sshCommandToConfig';
 import { getSshConfiguration, getSshConfigurationFiles, parseFailures, writeSshConfiguration } from '../SSH/sshHosts';
-import { documentSelector, pathAccessible } from '../common';
+import { documentSelector, isCpp, isCppOrCFile, isFolderOpen, pathAccessible } from '../common';
 import { instrument } from '../instrumentation';
 import { getSshChannel } from '../logger';
+import { SessionState } from '../sessionState';
 import { AttachItemsProvider, AttachPicker, RemoteAttachPicker } from './attachToProcess';
 import { ConfigurationAssetProviderFactory, ConfigurationSnippetProvider, DebugConfigurationProvider, IConfigurationAssetProvider } from './configurationProvider';
 import { DebuggerType } from './configurations';
@@ -129,6 +130,20 @@ export async function initialize(context: vscode.ExtensionContext): Promise<void
             }
         }
     }));
+
+    // Track active editor changes so "Run and Debug" button session state is kept up to date
+    // even if the language server (IntelliSense) is disabled.
+    updateBuildAndDebugSessionState(vscode.window.activeTextEditor);
+    disposables.push(vscode.window.onDidChangeActiveTextEditor(editor => updateBuildAndDebugSessionState(editor)));
+}
+
+export function updateBuildAndDebugSessionState(editor?: vscode.TextEditor): void {
+    if (editor && isCpp(editor.document)) {
+        void SessionState.buildAndDebugIsSourceFile.set(isCppOrCFile(editor.document.uri, editor.document.languageId));
+        void SessionState.buildAndDebugIsFolderOpen.set(isFolderOpen(editor.document.uri));
+    } else {
+        void SessionState.buildAndDebugIsSourceFile.set(false);
+    }
 }
 
 export function dispose(): void {
diff --git a/Extension/test/scenarios/SingleRootProject/tests/buildAndDebug.test.ts b/Extension/test/scenarios/SingleRootProject/tests/buildAndDebug.test.ts
new file mode 100644
index 000000000..5802e8b68
--- /dev/null
+++ b/Extension/test/scenarios/SingleRootProject/tests/buildAndDebug.test.ts
@@ -0,0 +1,50 @@
+/* --------------------------------------------------------------------------------------------
+ * Copyright (c) Microsoft Corporation. All Rights Reserved.
+ * See 'LICENSE' in the project root for license information.
+ * ------------------------------------------------------------------------------------------ */
+
+import * as assert from 'assert';
+import { suite, test } from 'mocha';
+import * as vscode from 'vscode';
+import { updateBuildAndDebugSessionState } from '../../../../src/Debugger/extension';
+import { SessionState } from '../../../../src/sessionState';
+
+suite("BuildAndDebug SessionState Tests", () => {
+    test("updateBuildAndDebugSessionState sets false when editor is undefined", () => {
+        updateBuildAndDebugSessionState(undefined);
+        assert.strictEqual(SessionState.buildAndDebugIsSourceFile.get(), false);
+    });
+
+    test("updateBuildAndDebugSessionState sets false for non-C/C++ editor", () => {
+        const mockEditor: any = {
+            document: {
+                uri: vscode.Uri.file("test.txt"),
+                languageId: "plaintext"
+            }
+        };
+        updateBuildAndDebugSessionState(mockEditor);
+        assert.strictEqual(SessionState.buildAndDebugIsSourceFile.get(), false);
+    });
+
+    test("updateBuildAndDebugSessionState sets true for C/C++ source file", () => {
+        const mockEditor: any = {
+            document: {
+                uri: vscode.Uri.file("main.cpp"),
+                languageId: "cpp"
+            }
+        };
+        updateBuildAndDebugSessionState(mockEditor);
+        assert.strictEqual(SessionState.buildAndDebugIsSourceFile.get(), true);
+    });
+
+    test("updateBuildAndDebugSessionState sets false for C/C++ header file", () => {
+        const mockEditor: any = {
+            document: {
+                uri: vscode.Uri.file("header.h"),
+                languageId: "cpp"
+            }
+        };
+        updateBuildAndDebugSessionState(mockEditor);
+        assert.strictEqual(SessionState.buildAndDebugIsSourceFile.get(), false);
+    });
+});