Vibe Coding Broke My App: How to Fix AI-Generated Code That Stopped Working
Your AI-built MVP looked great in the demo. Now it crashes in production, leaks data, and nobody can maintain it. A systematic plan for diagnosing, rescuing, and stabilizing vibe-coded projects — from a team that untangles these codebases every week.

If vibe coding broke your app — you are not alone, and the situation is fixable.
Vibe coding — building software by prompting AI tools like Cursor, Copilot, or ChatGPT instead of writing code manually — delivers impressive prototypes in a matter of hours. But these prototypes regularly fall apart under real-world conditions: security holes, missing error handling, untestable spaghetti code, and deployments that fail silently.
We know this not from reading articles. Of the last 40+ projects that came to us for AI code repair since early 2025, more than half were entirely or partially generated by AI. The failure patterns are so repetitive that we can predict the problems from the first git log: ten commits with the message "fix," no branches, direct pushes to main — and we already know there are no tests and deployment is manual.
The fix requires a systematic audit, targeted refactoring, and in many cases, professional intervention — what we call code rescue.
Why Vibe Coding Breaks Apps — Over and Over Again
The term "vibe coding" was coined by Andrej Karpathy in early 2025: you describe what you want in plain language, an AI model generates the code, and you accept the result based on feel — "seems to work" — instead of reviewing every line.
The approach instantly democratized software creation. Non-technical founders, designers, and product managers could suddenly build working MVPs in hours. And there is nothing wrong with that — the problem starts later.
"Works in a demo" and "production-ready" are completely different engineering standards. AI models optimize for plausibility: they generate code that looks correct and runs without immediate errors. They do not optimize for maintainability, security, or performance under load.
But the issue is not that AI is a "bad tool." AI is an excellent accelerator. The problem is that an accelerator without engineering discipline does not create software — it accelerates technical debt accumulation. Every prompt accepted without review is an architectural decision that nobody took responsibility for. Multiply that by hundreds of prompts — and you get an AI-generated codebase where every module made decisions locally, but nobody was accountable for the whole.
The 7 Most Common Reasons AI-Generated Code Breaks
After analyzing dozens of vibe-coded projects that came to us for rescue, we identified clear patterns. These are not isolated cases — they appear in virtually every AI-generated application that has never been reviewed by an experienced developer.
1. Security Vulnerabilities in Plain Sight
AI does not think about attackers. It writes the happy path. The result: hardcoded API keys in the frontend, missing input validation, SQL injections, and authentication that can be bypassed with a modified request.
But the most dangerous vulnerabilities are not the ones that are immediately visible. Here is a real pattern we find in every other AI-generated SaaS with payments:
// ❌ AI-generated payment handling code
app.post('/api/upgrade', async (req, res) => {
const { planId } = req.body;
const user = await User.findById(req.userId);
user.plan = planId; // Change plan
await user.save(); // Save
await stripe.charges.create({ // Charge payment
amount: getPlanPrice(planId),
customer: user.stripeId
});
res.json({ success: true });
});Looks fine at first glance. But if the Stripe call fails — the user has already been upgraded to a premium plan without being charged. No transaction, no rollback. In the test environment, Stripe always returns 200, so the bug does not surface until production.
// ✅ Correct order: charge first, then upgrade
app.post('/api/upgrade', async (req, res) => {
const { planId } = req.body;
const user = await User.findById(req.userId);
const charge = await stripe.charges.create({
amount: getPlanPrice(planId),
customer: user.stripeId
});
// Upgrade only if payment succeeded
user.plan = planId;
user.lastChargeId = charge.id;
await user.save();
res.json({ success: true });
});A real case from our practice: A SaaS product entirely generated in Cursor — the Stripe integration lived in client-side JavaScript, including the secret key. Anyone with browser DevTools could see it. We found the key within 40 seconds of opening the project.
2. Zero Test Coverage
AI tools almost never generate tests unless explicitly asked, and even then the tests are superficial — they check that a function does not crash but do not verify edge cases or business logic. A typical vibe-coded project: exactly 0% coverage. Every change is a gamble. You cannot refactor, update dependencies, or add features without risking silent breakage somewhere else in the application.
3. Spaghetti Architecture and Duplicated Logic
LLMs generate code one prompt at a time. Each response is locally coherent but globally chaotic.
Here is what we typically see — and here is how it gets fixed:
// ❌ Before refactoring: three components, three copies of the same call
// Dashboard.jsx
const userData = await fetch('/api/user').then(r => r.json());
// Profile.jsx
const user = await fetch('/api/user').then(r => r.json()).catch(() => null);
// Settings.jsx
const currentUser = await fetch('/api/user').then(res => res.json());Three components, three copies of the same call, three different error handling approaches. When the API changes — all three break, and you need to fix them in three places. And in a month there will be six.
// ✅ After refactoring: a single service with error handling
// services/userService.js
class UserService {
#cache = null;
#pending = null;
async getCurrentUser() {
if (this.#cache) return this.#cache;
if (this.#pending) return this.#pending;
this.#pending = fetch('/api/user')
.then(r => {
if (!r.ok) throw new Error(`User API: ${r.status}`);
return r.json();
})
.then(data => { this.#cache = data; return data; })
.finally(() => { this.#pending = null; });
return this.#pending;
}
invalidate() { this.#cache = null; }
}
export const userService = new UserService();A single entry point, unified error handling, caching, and protection against concurrent requests. Any API change — one fix in one place.
4. Deployment and Infrastructure Gaps
The AI built your app for localhost. It works on your machine. But there is no Dockerfile, no CI/CD pipeline, no environment variable management, no staging environment. The first deployment attempt exposes dozens of configuration issues — from missing environment variables to hardcoded localhost:3000 in API URLs.
A surprising detail: based on our observations, roughly 40% of the time spent rescuing AI projects goes not to code, but to infrastructure. Setting up proper CI/CD, staging environments, and secrets management often takes more time than fixing the business logic.
5. Database Schema That Does Not Scale
AI-generated database schemas work for 10 users but collapse at 1,000. No indexes, no migration strategy, no data validation at the schema level. We have seen a project where all user analytics were stored as JSON blobs in SQLite text columns — because that was the fastest way to get a "working" answer from the AI.
6. Dependency Chaos
AI models pull in whatever library seems right at the time of the prompt. The result: conflicting dependency versions, abandoned packages with known vulnerabilities, three different HTTP clients (axios, node-fetch, and native fetch) in the same project, and a package.json with 80+ dependencies, half of which are unused.
7. No Error Handling or Logging
When something goes wrong in production — and it always does — vibe-coded apps give you nothing. No structured logging, no error boundaries, no monitoring. The app crashes — the user sees a white screen. You see a white screen. Debugging means reading thousands of lines of AI-generated code with no comments and no clear entry points.
Case Study: SaaS Platform, 14,000 Lines, 3 Weeks to Stability
An anonymized case from our practice — typical in its problem structure.
What came in: A B2B SaaS built with React + Node.js + PostgreSQL, generated in Cursor over ~3 weeks. 14,000 lines of code. Stripe integration, user roles, analytics dashboard. Worked in the demo. In production — 500 errors on concurrent requests, Stripe keys leaking to the frontend, not a single test.
What we found during the audit:
- 11 security vulnerabilities, 3 of them critical (including Stripe secret key in the client bundle)
- The same database query duplicated in 7 places
- Zero test coverage
- No migrations — the schema was changed via direct
ALTER TABLEstatements in production - 23 npm packages with known vulnerabilities
What we did:
- Day 1-2: closed critical vulnerabilities, rotated all compromised keys
- Day 3-5: set up Sentry, CI/CD via GitHub Actions, staging environment
- Week 2: wrote integration tests for 5 critical paths, consolidated duplicated database queries
- Week 3: authentication refactoring, schema normalization, migration setup via Prisma
What we did not expect: the most labor-intensive part was neither the vulnerabilities nor the code refactoring. 60% of the time went into understanding the implicit dependencies between modules — which components actually depend on each other, what side effects a change in one place triggers. AI-generated code has no explicit architecture, and these connections have to be reconstructed from behavior, not from code. This is work that cannot be automated — only experience and systems thinking can handle it.
Result: the application runs stably, the client's team can make changes without fear, and API response time dropped 4x after adding indexes.
How to Fix Broken AI Code: A Step-by-Step Plan
Whether you are a founder staring at a broken MVP or a developer handed a vibe-coded project with the words "just fix it" — here is a systematic approach to fixing AI-generated code.
Step 1: Triage — What Actually Works?
Before touching the code, map the current state. Which features work correctly? Which ones have known bugs? Which are completely broken? Can you reliably deploy changes? Are there active vulnerabilities that need immediate patching?
We start every project with automated scanning: static code analysis (ESLint with security plugins, SonarQube), npm audit / pip audit for dependencies, and secrets detection via gitleaks. This gives an objective picture in an hour, not a day of manual reading.
Triage separates urgent fixes from long-term improvements and prevents the common mistake of starting a full rewrite when targeted fixes would suffice.
Step 2: Secure the Perimeter
Security is always first in line. Rotate all exposed API keys. Add input validation. Implement proper authentication. Set up HTTPS. Every day an insecure app runs in production, you are accumulating legal and reputational risks — and the longer you wait, the more expensive the consequences become.
Step 3: Set Up Monitoring Before Changing Code
Install error tracking (Sentry, LogRocket, or similar) and basic analytics before you start refactoring. You need to know what is breaking and how often. Without monitoring, you are fixing blind — and you will not know whether you made things better or worse.
Step 4: Write Tests for Critical Paths
You cannot test everything at once. Identify the 3-5 most critical user scenarios — signup, payment, core feature — and write integration tests for them. This gives you a safety net: when you start refactoring, the tests will show if something broke.
Step 5: Refactor Incrementally
Do not rewrite everything at once. Extract duplicated logic into shared services. Consolidate state management. Replace one problematic module at a time. Each change should be small enough to verify against the tests from the previous step.
Rescue or Rebuild: How to Make the Decision
The most expensive mistake when fixing AI code is choosing a full rewrite when a rescue would have been enough. Or the opposite — spending weeks patching a codebase that is architecturally unviable.
Rescue is justified when:
- The core architecture is sound — the problems are in the implementation, not the foundation
- The app works for most users most of the time
- The tech stack is modern and appropriate for the task
- The codebase is a manageable size with moderate module coupling
- The app needs to keep running while improvements are being made
Rebuilding is justified when:
- The fundamental architecture cannot support your requirements
- Security issues are so deep that patching creates more risk than starting fresh
- The cost of understanding the existing code exceeds the cost of rewriting it — this is the key indicator
- You have time: rebuilds typically take 2-4 months
How do we assess? Not by line count — 20,000 lines in a React SPA and 20,000 lines in an Express monolith represent completely different situations. We look at module coupling, dependency depth, the presence of clear entry points, and cyclomatic complexity of critical paths. If understanding a module takes longer than rewriting it — that is a signal.
In our experience, roughly 70% of vibe-coded projects can be rescued. The remaining 30% require a partial or full rebuild — but even then, the business logic and user research from the original prototype have immense value and carry over to the new architecture.
Why Not Just Ask AI to Fix Its Own Code?
This is the first question every vibe coder asks. And it is logical — if the AI wrote the code, maybe it can fix it too?
For an isolated bug — it sometimes works. If a specific function returns the wrong result, AI can often fix it. But for systemic problems — the ones this article is about — the "ask the AI again" approach most often leads to a vicious cycle: the fix breaks something else, fixing that breaks a third thing, and after four hours you have more problems than when you started.
The reason is simple: AI tools operate without memory of architectural decisions. Each prompt gets a locally optimal response that may contradict previous decisions. The AI does not see the system as a whole.
Professional developers bring exactly this — architectural accountability. They see why a change in the authentication module will cascade to the payment flow. They apply patterns proven across hundreds of projects. And importantly, the best engineering teams today actively use AI as a tool — but keep architectural decisions in human hands.
It is not about humans being "better" than AI or vice versa. It is about accountability. Someone needs to be responsible for the system as a whole — and for now, that can only be a person with an engineering mindset.
Our Approach to AI Code Rescue
At Webappski, we have been doing code rescue since 2015 — long before AI started generating code. Previously, projects came to us after outsource teams left; now they come after vibe coding. The patterns of chaos are surprisingly similar; the difference is the speed at which that chaos accumulates.
We do not promise that the fix will be quick or simple. Rescue projects always involve mess, compromises, and surprises. Sometimes during the audit we recommend pausing development for 1-2 weeks entirely — because every new commit to an unstable codebase increases the cost of the fix. This is not what clients want to hear, but honesty at the start saves months at the finish.
How our process works:
- Free diagnostic audit. Automated analysis + manual review of critical modules. The deliverable: a document with a specific list of problems, priorities, and a clear recommendation — rescue, partial rebuild, or full rebuild. Takes 2-3 business days. Free, no obligation.
- Priority security patch. If we find active vulnerabilities, we close them before starting the main work.
- Incremental stabilization. Tests, monitoring, CI/CD. The app stays live while we improve it. Typical stabilization timeline: 2-4 weeks for mid-size projects.
- Architectural refactoring. We restructure the codebase into maintainable, documented modules. Every decision is documented, every pattern is explained.
- Knowledge transfer. We do not create dependency on ourselves. Upon completion, your team (or future developers) gets a codebase they can actually work with, and documentation that explains why, not just what.
We work with React, Angular, Vue, Next.js, Node.js, Python, and other modern stacks. The specific AI tool does not matter — the failure patterns are the same for Cursor, Copilot, ChatGPT, Claude, and the rest.
How to Prevent the Next Breakdown: Best Practices
Vibe coding is a legitimate development accelerator when used correctly. The key is treating AI-generated code as a draft, not a finished product.
- Review every AI output. Read the code before accepting it. If you cannot understand what it does — that is a red flag, not a reason to hit Accept.
- Require tests. Ask the AI to generate tests alongside features. Add this to the system prompt — it will not do it on its own.
- Version control from day one. Git commits should be small and descriptive. If something breaks — you can roll back to a working state.
- Set architectural rules upfront. Define the folder structure, state management approach, and API patterns before writing code. Feed these constraints to the AI in the system prompt or in
.cursorrules. - Schedule professional reviews. Even a two-hour code review from an experienced developer every two weeks can catch problems before they snowball.
- Never deploy without a security audit. Before every production deployment, someone who understands security should review authentication, authorization, and data handling.
Conclusion: Your Vibe-Coded App Is Not Doomed
The code may be chaotic, but the product thinking, user scenarios, and business logic behind it have real value. With the right approach — systematic triage, security-first fixes, incremental refactoring — most AI-generated projects can be transformed into stable, maintainable software.
The worst decision is doing nothing. Vulnerabilities do not heal themselves; technical debt grows exponentially. The second most useless decision is asking the same AI to fix its own mistakes in a loop.
If you already have a suspicion that something is wrong with your app — you are probably right. The sooner you run an audit, the cheaper the fix will be.
Get a free diagnostic audit →
What is included: automated code analysis + manual review of critical modules. What you get: a document with a specific list of problems, priorities, and a recommendation (rescue / partial rebuild / full rebuild). Timeline: 2-3 business days. Cost: free, no obligation.
FAQ: Fixing Broken AI-Generated Code
Can I fix a vibe-coded app by asking the AI again?
For isolated bugs — sometimes yes. For systemic problems (architecture, security, scaling) — no. AI has no architectural memory: each fix prompt may solve one problem while creating new ones. When you notice you are fixing things in circles — that is the signal to call in an engineer.
How much does it cost to rescue a vibe-coded project?
It depends on the severity. A security patch and basic stabilization take days. A full architectural refactor of a mid-size application typically takes 2-6 weeks. Start with a free audit — it will show you the scope before you commit to a decision.
Should I rebuild from scratch or fix what I have?
About 70% of projects can be rescued with targeted refactoring — it is faster and cheaper. A rebuild is justified when the architecture fundamentally cannot support your requirements. A professional audit will show which path is more cost-effective.
What if we have no documentation at all?
That is the norm for vibe-coded projects — the vast majority of our clients have neither documentation nor a README. Part of our process is reverse-engineering the codebase and creating documentation from scratch.
What if the code was written by multiple AI tools in sequence?
We see this frequently: started in ChatGPT, continued in Cursor, finished in Copilot. Each tool brought its own patterns and style. This makes diagnosis harder, but does not change the approach — we work with the result, not with the history of how it was created.
What if the project is already in production with real users?
That describes the majority of our clients. Incremental stabilization exists precisely for this — the app continues to run while we improve it. Zero minutes of downtime.
Is vibe coding always bad?
No. Vibe coding is excellent for rapid prototyping, idea validation, and low-risk internal tools. Problems arise when a prototype gets shipped as production software without professional review. AI is an accelerator. But an accelerator without a steering wheel is not innovation — it is a crash.