The Error Message Decoder

NOTE

Use this page as a prompt reference. Every file below is built to be handed straight to an AI. Download it, drop it into Claude, ChatGPT, Cursor, or Lovable, and say "use this as my playbook." The prompts on this page are copy-paste ready.

I hit an error in my app. The full error message is pasted below.

Before you change ANY code, do this in order:

1. EXPLAIN: Tell me what broke in plain English. 2 sentences maximum,
   no jargon. Pretend I have never written code.

2. CLASSIFY: Tell me which of these it is (pick exactly one):
   a) A problem in the app's own code
   b) A missing or wrong key/credential (an API key, a password, a setting)
   c) An outside service being down or unreachable
   d) A limit being hit (rate limit, quota, plan limit, size limit)
   Say which one and why you think so.

3. PROPOSE: Describe the SINGLE smallest change that would fix it.
   One change only. If you think it needs several changes, tell me the
   first one and stop there.

4. WAIT-CHECK: If the fix requires something only I can do (paste a key,
   upgrade a plan, wait for a service to come back), say so and stop.
   Do not write workaround code for a problem that isn't code.

5. APPLY: Make only that one change. Do not refactor, do not clean up,
   do not improve anything else you noticed, do not touch any other file.

6. REPORT: Tell me exactly what you changed (which file, what it does now
   that it didn't before) and what I should see when I try again.

If the error message doesn't give you enough to be confident, say
"I'm not sure yet" and tell me the ONE thing to check or paste next.
Guessing is worse than asking.

HERE IS THE ERROR:
[PASTE YOUR FULL ERROR MESSAGE HERE]

WATCH OUT

Paste the whole error. The instinct is to paste just the first line. The useful part (which file, which line, which service said no) is often in the middle of the wall of text. More context in, better diagnosis out.

My app shows a blank page (or a white screen). There is no error message
visible to me. Do NOT start changing code. A blank page means something
crashed before the screen could load, and the real error is hidden.
Find it first:

1. HUNT: Look for the hidden error. Check, in order:
   a) The browser console (the log web browsers keep of what went wrong;
      if I need to open it myself, tell me the exact keys to press:
      usually F12 or Cmd+Option+J, then the "Console" tab)
   b) The build or deploy logs (the record of what happened when the
      app was assembled and published)
   c) The server logs, if this app has a backend

2. If you can see those logs yourself, read them and quote the first
   red/error line you find. If you cannot see them, tell me exactly
   where to click to find them and what to copy back to you.

3. Once we have the real error, treat it like this: explain it in plain
   English (2 sentences max), classify it (app code / missing key /
   service down / limit hit), propose the single smallest fix, apply
   only that, and report what you changed.

Do not rewrite any component, page, or config "to be safe" while we
are still hunting. One error, one fix.

STOP. We have tried to fix this at least twice and it is getting worse,
not better. Do not attempt another fix yet. Do this instead, in order:

1. LIST: Write out every change you have made since the original error
   first appeared. Every file touched, every setting changed, every
   package added. A numbered list. If you are not sure you remember
   them all, say so.

2. SORT: For each change, answer honestly: did it help, did it do
   nothing, or did it make things worse or add a new error?

3. REVERT: Put back everything that did not clearly help. I want to
   get back to having ONE problem, the original one, instead of the
   original problem plus your patches. Tell me each thing you put back.

4. CONFIRM: Tell me what the current error is NOW, after the cleanup.
   Quote it exactly. It may be the original error again. That is good.
   That is progress.

5. DIAGNOSE FRESH: Now treat that error as brand new. Explain it in
   plain English (2 sentences max), classify it (app code / missing
   key / service down / limit hit), and propose the single smallest
   fix. Do not apply it yet. Wait for my go.

Rule from here on: one change per attempt, and you report what changed
after each one. No batches.

I'm getting an authentication error (401/403/invalid API key). Do not
rewrite any app code; this is a credentials problem, not a code problem.

1. Tell me exactly which service is rejecting us (the name of it).
2. Tell me exactly where in this project that service's key is supposed
   to live (the name of the setting or environment variable, which is a
   named slot where apps store secrets).
3. Tell me whether that slot is currently empty, or filled with something
   that looks wrong (wrong format, extra spaces, quotes around it).
4. Tell me the exact page where I get a fresh key for this service, and
   the exact place in my tool where I paste it (which menu, which button).
5. Do not put the key directly into the code files, ever. Keys live in
   the settings slot only.

I will paste the new key myself. After I do, tell me how to confirm it
worked.

I'm getting a CORS error (the browser safety rule that blocks one website
from calling another server directly). The full error is pasted below.

1. Explain in one sentence which two addresses are refusing to talk:
   my app's address and the server it tried to call.
2. Tell me which fix applies here (pick one, smallest first):
   a) The service I'm calling has a setting where I add my app's address
      to its allowed list. If so, tell me where that setting is.
   b) The call should be made from my app's backend instead of from the
      browser (servers are not bound by this browser rule). If so, move
      ONLY this one call to the backend. Do not restructure anything else.
3. Do NOT "fix" this by disabling security, using a random public proxy
   from the internet, or adding headers to my own app (my app's headers
   cannot fix this; the permission has to come from the other side or
   the call has to move).
4. Apply the one fix, then tell me what you changed and how to test it.

HERE IS THE ERROR:
[PASTE THE CORS ERROR HERE]

The build failed (the app can't start because of a code mistake). The
full error is pasted below.

1. The error names a file and usually a line number. Go to exactly that
   spot. Quote me the broken line.
2. Explain in one plain-English sentence what's wrong with it (missing
   bracket, misspelled name, importing a file that doesn't exist, etc.).
3. Fix ONLY that line (or the smallest edit that resolves it). Do not
   rewrite the file, do not "clean up while you're in there", do not
   touch any other file.
4. If fixing it reveals a SECOND build error, stop and show me the new
   error before fixing it. One error per attempt.
5. Report: the before line, the after line, and confirmation the build
   passes.

HERE IS THE ERROR:
[PASTE THE BUILD ERROR HERE]

I'm hitting a rate limit or quota error (429 / quota exceeded). This is
a usage ceiling, not a code bug, so do not rewrite app logic to "fix" it.

1. Tell me exactly which service's limit I hit, and which kind:
   a) Too many requests too fast (resets in minutes)
   b) A daily/monthly cap (resets on a schedule)
   c) A spending or plan limit (resets when I pay or upgrade)
2. Tell me, from the error message, when it resets or what upgrading
   costs, if that information is in there.
3. Tell me if my app is calling this service more than it needs to
   (for example, calling it on every keystroke instead of on submit,
   or calling it in a loop). If yes, propose the ONE change that cuts
   the most calls, and apply only that.
4. If the app's usage is reasonable and I simply need a bigger plan,
   say so plainly with the service's pricing page, and change nothing.

PAYOFF

Reverting costs you an afternoon of changes. A broken app costs you the project. The builders who last aren't the ones who never break things; they're the ones who can always get back to a version that works.

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