Fix · Node, npm and build

Strange errors after changes: clean caches and reinstall

What you may see

The same code gives different errors, or old errors keep coming back
I switched branches or Node versions

Most likely cause

Generated folders (.next, dist, node_modules) can hold leftovers from another version of the project.

Check first (about two minutes)

Confirm there are no unsaved edits you would lose (git status).

The fix prompt

What you type here never leaves your browser. The search runs on this page, and nothing is sent to a server or to an AI.

The exact error or what you see

What you did before it happened

Kept only in this browser, on this device. Keys and passwords are removed before anything is saved.

Prompt language

You are a patient senior engineer who knows Node.js, npm and build tools and explains them to people who are not developers. I am not a developer, so explain every step in plain words and tell me exactly which button, menu or command you mean. If you are not sure about something, say so; do not guess.

THE PROBLEM
Strange errors after changes: clean caches and reinstall

THE EXACT ERROR OR WHAT I SEE
[paste the exact error here]

WHAT I DID BEFORE IT HAPPENED
[write in a few words what you did before it happened]

MOST LIKELY CAUSE
Generated folders (.next, dist, node_modules) can hold leftovers from another version of the project.

DO THESE STEPS, IN THIS ORDER
1. Run git status first and tell me if anything unsaved could be lost.
2. Delete only the generated folders (.next, dist, build cache) and keep my source files and .env.
3. If it persists, remove node_modules and run npm ci (from the lock file), not a fresh npm install.
4. Start the dev server again and test.
Stop and tell me if what you see does not match a step. Do not skip ahead.

CHECK THAT IT WORKED
- The old error is gone and the app runs on the first try.
Tell me exactly what I should see on the screen when it works.

DO NOT CHANGE
- Do not delete package-lock.json, .env, or any source folder.
- Anything I did not ask about: the design, the text, other pages, other settings or the data.
- Do not delete files, data or branches, do not reset or force-push, and do not rewrite history, unless you first show me exactly what would be lost and I say yes.
- Do not paste, print or ask me to paste a password or secret key into this chat. If one is needed, tell me which settings page of the right service to store it in.

WHEN YOU FINISH
Explain in simple words what you changed (file by file or setting by setting), why you changed it, and how I can undo it.

Paste it into Claude, ChatGPT, Gemini or Cursor, then follow what it says.

After you tried it, did it work?

Steps

Run git status first and tell me if anything unsaved could be lost.
Delete only the generated folders (.next, dist, build cache) and keep my source files and .env.
If it persists, remove node_modules and run npm ci (from the lock file), not a fresh npm install.
Start the dev server again and test.

Do not do this

Do not make this the first answer to every error: read the error first.
Do not delete package-lock.json, .env, or any source folder.

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