VS Code IntelliSense not working? Quick fixes for autocomplete & missing signature help

Last Updated: September 14, 2025 · For: Beginner to Intermediate VS Code Users

Quick Summary

When VS Code's autocomplete, parameter hints (Signature Help), and "Go to Definition" stop working, it's usually due to one of four issues: incorrect language mode, language server errors, extension conflicts, or workspace trust problems.

This typically manifests as IntelliSense not working with broken autocomplete, or a non-functional Go to Definition. The fixes below will get you back up and running in under 5 minutes.

📋 Table of Contents

• Quick Fix (3 minutes)
• Problem Symptoms
• Detailed Solutions
• Final Checklist
• Frequently Asked Questions

Quick Fix (3 minutes)

⚠️ Try This First!

1. Check the language mode in the bottom status bar (.ts → TypeScript, .py → Python)
2. Open Command Palette (Ctrl+Shift+P on Windows/Linux, ⌘+Shift+P on macOS) → run Developer: Reload Window
3. Restart the language server for your language:
   • TypeScript/JavaScript: TypeScript: Restart TS Server
   • Python: Python: Select Interpreter → then Python/Pylance: Restart Language Server
   • C/C++: C/C++: Reset IntelliSense Database

VS Code Command Palette with 'Developer: Reload Window' command

Problem Symptoms

• Autocomplete suggestions don't appear or only show basic word completions
• Parameter hints (Signature Help) are missing
• F12 (Go to Definition) doesn't work
• Status bar shows Plain Text instead of the correct language
• Restricted Mode banner appears when opening folders

Detailed Solutions

1️⃣ Verify Correct Language Mode

Click the language name in the bottom-right of the status bar and select the correct language for your file extension.

2️⃣ Check Essential Extension Status

Make sure required extensions for your language are enabled:

• JavaScript/TypeScript: TypeScript and JavaScript Language Features (built-in)
• Python: Python + Pylance
• C/C++: C/C++ (ms-vscode.cpptools)

3️⃣ Reload VS Code Window and Language Servers

1. Open Command Palette (Ctrl+Shift+P / ⌘+Shift+P) → Developer: Reload Window
2. Then restart language-specific servers:
   • TypeScript: Restart TS Server
   • Python/Pylance: Restart Language Server
   • C/C++: Reset IntelliSense Database

4️⃣ Configure Workspace Trust

If a Restricted Mode banner appears, open the Trust editor and mark the folder as trusted.

5️⃣ Verify Project Configuration Files

• TS/JS: Ensure tsconfig.json or jsconfig.json exists and verify include paths
• Python: Run Python: Select Interpreter and confirm the correct virtual environment
• C/C++: Use C/C++: Edit Configurations (UI) to check includePath and standards

6️⃣ Diagnose Extension Conflicts

• Command Palette: Extensions: Disable All Installed Extensions (temporary)
• Terminal: code --disable-extensions
• If the issue disappears, run Help: Start Extension Bisect to identify the culprit

7️⃣ Reset User Settings

Open Preferences: Open User Settings (JSON) and remove suspicious configuration entries.

✅ Final Checklist

• Language mode matches file extension
• Required extensions are enabled
• Window/language server restart completed
• Workspace is trusted
• Configuration files are correct
• Extension conflict check completed

Frequently Asked Questions

No autocomplete appears and it shows Plain Text.

Open Command Palette → change Language Mode to match your file extension.

TypeScript/ESLint stopped working after switching Git branches.

Open Command Palette → run TypeScript: Restart TS Server, then Developer: Reload Window.

Only Python IntelliSense isn't working.

Open Command Palette → run Python: Select Interpreter → choose correct environment → then Python/Pylance: Restart Language Server.

I've tried everything but nothing works.

Completely close and restart VS Code, or temporarily move your user data directory. (⚠️ Advanced users only)

📚 References

1. VS Code Official — IntelliSense
2. VS Code Official — Workspace Trust
3. VS Code Official — Python: Environments & Select Interpreter