If your code is not working, it almost always falls into one of six root causes: expired, invalid, region-locked, rate-limited, scan-failure, or tooling-failure. Identify which one you have, apply the matching fix, and you are done in under five minutes. This guide covers promo codes, 2FA codes, QR codes, and Claude Code in a single decision tree, so you never have to guess or tab-switch for an answer.
Why does my promo code say it's not working even though it looks valid?
A promo code can look valid and still be rejected because the retailer's check happens server-side, not on your screen. The code string is fine; the conditions attached to it are not. "Code not working" covers several unrelated failures, from promo codes to 2FA to Claude Code errors (Anthropic's docs cover that last category), but promo codes are the most common and the most fixable.
The four reasons promo codes fail
| Reason | What you see | Quick check |
|---|---|---|
| Expired | "Code is invalid or expired" | Check the promo's end date, not the code itself |
| Region lock | "Code not valid in your region" | Compare the promo's country list to your account's billing country |
| One-per-account | "You've already used this code" | Try a logged-out or new account to confirm |
| Minimum spend | "Code not applicable to cart" | Add the qualifying item or hit the stated threshold |
Dodgers and McDonald's codes: what makes them different
Sports and fast-food promos (Dodgers ticket codes, McDonald's app deals) are usually single-use or tied to a specific event, app install, or loyalty account. If a McDonald's code fails, it's often because it must be redeemed in the app while logged in, not on the website. Dodgers codes are frequently event-gated and die at first pitch. When a code fails for a reason you can't see, screenshotting the error and asking for the likely cause in your flow, without tab-switching, gets you a diagnosis faster; our quiz tool works the same way for trivia-style questions.
Why is my authentication or 2FA code not working?
Most 2FA failures come down to one of four causes: the code expired, the code is for the wrong account, the app's clock has drifted, or you're hitting a resend throttle. Each has a different fix, and guessing wrong wastes your attempts.
Clock drift and TOTP codes
Authenticator apps like Google Authenticator generate 6-digit codes that rotate every 30 seconds. If your phone's clock is even a minute off from the server's, the code you type will read as invalid every time. Fix: enable automatic date and time in your phone settings, or in Google Authenticator go to Settings and use "Time correction for codes." This solves the majority of "my authenticator code is wrong" cases.
SMS vs authenticator app codes
SMS codes fail differently. They can arrive late (carriers delay them), expire in as little as a few minutes, or land on the number tied to an old account. If you requested multiple codes, only the newest one works. Wait 60 seconds, request once more, and use that code immediately.
If you're mid-login and can't tell whether the problem is the code itself or something else on screen, an overlay tool like answerplz reads the error message and tells you which failure type you're looking at in one click, no copy-paste or tab-switching. We break down how that compares with using the ChatGPT desktop app directly at https://answerplz.com/vs/chatgpt.
Why is my QR code not scanning at all?
Most QR scan failures come down to one of four causes: low contrast, physical damage, wrong distance, or a blocked camera. A pale code on a white receipt, a creased code on a poster, or a phone held too close (the lens can't focus under about 4 inches) will all fail silently. Start by moving 6-12 inches away, holding steady, and letting the camera auto-focus before you tap.
If it still won't scan, check that the app actually has camera permission: on iPhone, go to Settings > Camera and confirm Camera access is on, per Apple's guide to scanning QR codes. Also make sure you're using the Camera app itself, not a photo of the code from your gallery.
If the code is on your screen rather than in the real world, screenshot it and ask directly — answerplz reads what's on screen and answers in one click, no switching windows. We compare how that stacks up against Crade in our answerplz vs Crade breakdown.
Why is my QR code not working on iPhone specifically?
iPhone QR failures usually trace back to one of four things: the Camera's QR setting is off, you're using Control Center's Code Scanner instead of the Camera app, Low Power Mode is throttling focus, or the link behind the QR opens in a way Safari doesn't handle.
Check the Camera setting first
Open Settings, tap Camera, and make sure Scan QR Codes is toggled on. If it's on and scanning still fails, hold the phone 4-8 inches from the code and tap the screen to lock focus. Low Power Mode can slow camera focus on older iPhones, so toggle it off in Settings > Battery and try again.
When the QR scans but the link fails
If you see the yellow notification banner but nothing opens, the problem is the link, not the scan. Tap the banner instead of waiting, or long-press it to choose which app opens the URL. Some QR links only work in specific apps, and iOS may route them to Safari by default.
Why is Claude Code not working and how do I fix it?
Claude Code failures usually fall into three buckets: an expired login session, a network or proxy problem, or an outdated CLI version. Each has a fix you can run in under two minutes.
Auth and session errors
If you see an authentication error or repeated permission prompts, your session token has expired. Run the login command again and re-authenticate in your browser. If you work behind a corporate proxy, Claude Code may be blocked from reaching the API; check your proxy settings and make sure the CLI is allowed through. The Anthropic documentation covers setup and troubleshooting steps for both cases.
When the CLI itself fails to start
If the command errors out before any prompt appears, check your Node version first; an old runtime is the most common cause. Update the CLI to the latest version, since older builds break when the API changes. Still stuck? Clear the CLI's cache and config directory, then reinstall. If none of that works, the failure is on Anthropic's side, and waiting a few minutes beats debugging.
How do I tell which type of 'code not working' problem I have?
Most "code not working" errors fall into one of four buckets: a rejected promo code, a failed authentication or 2FA code, a QR code that won't scan, or a broken coding tool. The fastest diagnostic is to ask what kind of code is on your screen and what the failure looks like. A promo code fails with a red message at checkout, a 2FA code fails with "incorrect code," a QR code fails silently, and a coding tool fails with a terminal error. Those four symptoms point to four different fixes.
The decision tree
Start with the question: is the code something you type, scan, or run?
If you type it into a checkout box and get rejected, it's a promo code problem. If you type a six-digit number and it bounces, it's an authentication problem. If you point your camera at a square and nothing happens, it's a QR code problem. If you're running a command-line tool and the terminal spits an error, it's a coding tool problem.
Then check one thing: did the code ever work before? A promo code that worked yesterday and fails today is usually expired or already used. A 2FA code that always fails is almost always a clock-sync issue on your phone. A QR code that scans on one device but not another is a brightness or lens problem, not a broken code. A coding tool that worked before an update is a version or config problem. That single question, "did this ever work," cuts your five-minute diagnosis down to about thirty seconds, because fresh failures and repeat failures have different root causes almost every time.
Symptom-to-cause table
- Red "invalid code" at checkout: expired, region-locked, or minimum-spend not met. Check the terms line.
- "Incorrect code" on a 2FA prompt: phone clock drift, or you typed a stale code. Regenerate and retype fast.
- Camera ignores a QR square: low contrast, glare, or the code is too small for your lens distance.
- Terminal error from a coding tool: read the first error line, not the last. It usually names the missing file, version, or permission.
Match your symptom to a row, and the linked fix in the matching section above takes under five minutes.
When should I give up on a code and contact support instead?
Three signals mean the code is dead, not misused: it's region-locked to a country you're not in, the redemption counter has hit its cap, or your account has been flagged for prior promo abuse. No amount of retyping fixes any of these. One special case: if your 2FA code is rejected repeatedly, the fix is usually your device clock, not the code itself. Time-based codes fail when your phone drifts more than the allowed window, which is why the Google Authenticator documentation tells you to sync your clock in settings before anything else. When you do contact support, include the code exactly as written, the URL or store you tried, a screenshot of the error, your account email, and the timestamp. That's everything they need to confirm a dead code in one reply, and it spares you the three-message back-and-forth.
How do I debug a code error without leaving my screen?
The copy-paste loop is the slow part: screenshot or select the error, switch to your chatbot tab, paste, wait, switch back. answerplz collapses that into one click. Hit the global hotkey, it reads your screen, and the answer appears as an overlay in context, whether the failure is a rejected promo code, a 2FA mismatch, or a stack trace. Free tier, no card required, $5-$20/mo individual plans.
What answerplz does well and where it falls short
The honest version: it wins on speed and context because nothing leaves your screen. Crade, Highlight AI, Jarvis (getjarvis.eu), and LiveQ occupy the same screen-assistant category, so try each against your actual failure type. Where answerplz falls short: it answers what's on screen, so if the fix needs a file it can't see, your terminal history, or multi-step agentic work, ChatGPT Desktop App (chatgpt.com) handles that better. It's a lookup layer, not a full coding agent.