Autocomplete was working an hour ago. Now you type a method name and nothing shows up — no suggestions, no parameter hints, no little popup confirming you spelled it right. Nothing crashed. No error appeared. VS Code just quietly stopped helping.

The usual response is to reinstall the language extension, or VS Code itself, and hope. That fixes it by accident sometimes, which is exactly what makes it a bad habit — it works often enough to seem right, so the actual cause never gets identified, and the same thing happens again next week.

What’s actually happening

IntelliSense (VS Code’s name for autocomplete, parameter hints, and inline suggestions together) isn’t a single feature — it’s the output of a language server running in the background, analyzing your code. When it goes quiet, there are exactly three places that chain can break:

  1. The language extension isn’t installed or is disabled. No extension, no language server, no IntelliSense for that file type — full stop.
  2. VS Code is pointed at the wrong interpreter or runtime. For Python, Node, and similar languages, the language server needs to know which environment you’re actually working in. Point it at the wrong one (or none), and it can’t analyze anything correctly.
  3. The language server itself has stalled, usually after a large refactor, a dependency change, or the project just being open a long time. The extension is fine, the interpreter is fine, the background process just needs a restart.

Reinstalling only ever addresses cause 1. If your real problem is 2 or 3, reinstalling changes nothing — which is why it “randomly” doesn’t work half the time people try it.

The fix, step by step

  1. Check the Extensions view for the language you’re working in. Missing or disabled — that’s cause 1, solved by installing or re-enabling it.
  2. Check the Status Bar for the interpreter or runtime VS Code is currently using. If it’s wrong, or blank, open the Command Palette (Ctrl+Shift+P / Cmd+Shift+P) and run: 
    Python: Select Interpreter
    (or the equivalent for your language) and point it at the right one.
  3. Restart the language server before assuming anything is actually broken: 
    Developer: Reload Window
    This alone resolves a surprising share of “IntelliSense stopped working” reports — it’s a stalled background process, not a misconfiguration.

Two mistakes worth knowing about ahead of time

Blaming VS Code for what’s actually a project problem. A large, uninitialized project — missing dependencies, no virtual environment set up — can leave the language server with nothing to analyze. It’s not a VS Code bug at that point; it’s the language server correctly reporting that it can’t see what it needs to see. If reloading the window doesn’t help, check whether the project itself is fully set up before troubleshooting the editor further.

Not realizing Go to Definition and Rename Symbol break for the same reason. Both features rely on the exact same language server IntelliSense uses. If autocomplete is silent, don’t troubleshoot those separately — fixing the language server fixes all three at once, and troubleshooting them as unrelated problems just means solving the same root cause three times.

A debugging habit that works

When IntelliSense goes quiet, resist the pull toward the drastic fix first. Check the Extensions view, check the Status Bar for the active interpreter, then reload the window — in that order, before anything more invasive. All three take under a minute combined, and between them they cover the actual three causes instead of gambling on a reinstall that only fixes one of them.