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Troubleshooting

Vercel Build Failed: Read These 3 Spots in the Log

When a Vercel deploy goes red, the build log already names what broke — if you know where to look. Three log positions, plus the six most common failure modes and exact fixes.

Published: Updated: Author: AI Productivity Guide Team 🌐 查看中文版本

The red Build Failed row in your Vercel deployments isn’t the scary part. The scary part is scrolling thousands of log lines and not finding the actual error. A Vercel build log is a chronological mash-up: npm install warnings, TypeScript notices, framework progress bars, all stacked together, and the real error is routinely buried under green info lines.

Fastest fix: open the failed deployment, click Building to expand the log, and jump to the very bottom. The last stack trace and the line Error: command "..." exited with N name the cause almost every time. 137 means out of memory, 1 means a build error (type error, missing module, missing env var). This guide shows the three log spots to scan in 30 seconds, then maps the six most common failure modes to exact fixes. It applies to Next.js, Astro, Vite, Remix, SvelteKit, and any framework on Vercel.

The three log positions to read first

Regardless of cause, scan these three before anything else:

  1. The last stack trace — the block at the very bottom. When Node throws, the first two lines after the message are the real cause.
  2. The exit-code line — usually the second-to-last line: Error: command "..." exited with N. See the table below for what each N means.
  3. Highlighted error lines — Vercel colors error: and Error: red. Use the browser’s Find (Cmd/Ctrl+F) for error to jump between them and skip the noise.
Exit codeMeaningWhere to look next
137Out of memory (SIGKILL)Memory section below
1Generic build errorThe last stack trace — type error, missing module, or missing env var
2Shell/command misuseYour build script in package.json
134Process aborted (SIGABRT)Native module or assertion failure

Common causes, by hit rate

Ordered highest-frequency first.

1. Node / dependency version drift between local and Vercel

By far the most common. As of June 2026 a new Vercel project defaults to the latest supported Node LTS, which is 24.x (22.x and 20.x are also available). If your machine still runs Node 20 and Vercel runs 24, native modules (sharp, canvas, bcrypt, better-sqlite3 — anything with native bindings) hit ABI incompatibility and fail to compile.

gyp ERR! build error
node-pre-gyp ERR! Tried to download(404): https://...

How to spot it: the top of the log shows Running "install" command and Detected ... Node.js version. Compare it to your local node -v. One or more major versions apart points here.

Fix: pin the version on both sides. In the dashboard, Settings → Build and Deployment → Node.js Version and pick the dropdown value that matches local. Then lock it in package.json so the repo is the source of truth:

{
  "engines": {
    "node": "22.x"
  }
}

The engines.node major version overrides the dashboard dropdown, so once it’s committed every build is reproducible.

2. Production env var missing or misspelled

A build-time variable (NEXT_PUBLIC_SUPABASE_URL, SANITY_PROJECT_ID) was added only to the Preview scope, never Production. Or it was typed as SUPABSE_URL in the dashboard.

Error: Environment variable NEXT_PUBLIC_SUPABASE_URL is not set
  at Object.<anonymous> (/vercel/path0/lib/supabase.ts:4:5)

How to spot it: search the log for is not set or undefined next to a variable name you recognize.

Fix: Settings → Environment Variables. When you add a variable, the All Environments checkbox is on by default — leave it on so the value applies to Production, Preview, and Development at once. If you need different values per scope, uncheck it and add the variable once per environment. Note that NEXT_PUBLIC_* (and similar framework-prefixed) variables are inlined at build time, so changing one requires a fresh deploy, not just a restart.

3. OOM — build exceeds memory (exit 137)

Every Vercel build container is allocated 8192 MB of memory (8 GB), and this is the same on Hobby and Pro. Large Next.js apps, thousand-page static generation, or heavy TypeScript inference can blow past it, and the kernel kills the process with SIGKILL.

<--- Last few GCs --->
<--- JS stacktrace --->
FATAL ERROR: Reached heap limit Allocation failed - JavaScript heap out of memory
Error: command "npm run build" exited with 137

How to spot it: the log tail shows exited with 137 or heap out of memory.

Fix: raise Node’s heap ceiling. Vercel’s own guidance is --max-old-space-size=6144, not 8192 — leaving ~2 GB of headroom keeps the Node process itself from being the thing that gets OOM-killed. Set it in the build script:

{
  "scripts": {
    "build": "NODE_OPTIONS='--max-old-space-size=6144' next build"
  }
}

If you’d rather keep it out of the repo, add NODE_OPTIONS = --max-old-space-size=6144 under Settings → Environment Variables. If the build still OOMs after that, the real fix is reducing memory pressure (paginate static generation, disable production source maps, experimental.webpackBuildWorker) — on Pro/Enterprise you can also enable Enhanced Builds, which bumps the container to 16 GB of memory, 8 CPUs, and 58 GB of disk.

4. TypeScript strict / lint errors skipped locally

next build and astro build run a type check (tsc --noEmit for Astro; Next.js type-checks during build) and fail on the first error. Local npm run dev skips full type checking, so the error never surfaces in development.

Type error: Property 'user' does not exist on type 'Session | null'.
  47 | export default function Page({ session }) {
  48 |   return <div>{session.user.name}</div>
                              ^

How to spot it: the log contains Type error:, a string like error TS2339, or an ESLint error with a specific file and line.

Fix: run the production build locally — npm run build, not npm run dev — and fix the type error before pushing. Suppressing it with typescript.ignoreBuildErrors in next.config.js will make the build pass but ships the bug, so prefer fixing the type.

5. Monorepo Root Directory misconfigured

The repo is a monorepo (pnpm workspace, Turborepo, Nx) but the Vercel project’s Root Directory is empty or points at the wrong subdirectory. The build can’t find the right package.json or installs the wrong dependencies.

Error: No Next.js version detected. Make sure your package.json has "next" in either "dependencies" or "devDependencies".

How to spot it: right after Cloning ..., the Running "install" step shows a working directory that isn’t your app’s folder.

Fix: Settings → Build and Deployment → Root Directory → Edit, and set it to the folder that holds the app’s package.json (for example apps/web). Redeploy after changing it.

6. Case-sensitive filename mismatch (macOS vs Linux)

macOS is case-insensitive by default, so Header.tsx and header.tsx resolve to the same file. Vercel builds on Linux, which is strict. Code that imports './header' while the file is Header.tsx works locally and throws “module not found” on Vercel.

Module not found: Can't resolve './header' in '/vercel/path0/components'

How to spot it: the error is Can't resolve './xxx' but you’ve confirmed the file exists locally — that’s a case mismatch ~99% of the time.

Fix: make the import string match the file’s exact casing. Because Git tracks filename case loosely on macOS, rename through Git so Linux sees it: git mv Header.tsx header.tsx (or fix the import), then commit.

Shortest path to a fix

Step 1: Reproduce Vercel’s build environment locally

# Match Vercel's Node version (use the version your dashboard / engines.node shows)
nvm use 22

# Wipe caches and rebuild from scratch
rm -rf node_modules .next dist
npm ci            # strict lockfile install, same as Vercel
npm run build     # the production build, not dev

Roughly 90% of the time you’ll reproduce the failure right here, where iteration is instant. npm ci (not npm install) is what makes this faithful — it installs the exact lockfile, the same as Vercel.

Step 2: Map the log keyword to the fix

Log keywordReal causeFix
exited with 137 / heap out of memoryOOMNODE_OPTIONS=--max-old-space-size=6144, or Enhanced Builds
is not set / undefined + a var nameMissing env varAdd it under the correct scope in Environment Variables
Type error: / error TS2339Strict TSRun npm run build locally and fix the type
Can't resolve './...'Case mismatchRename the import to match the file’s exact casing
gyp ERR! / node-pre-gypNative module + Node ABIPin engines.node to match, or swap for a binding-free package
No Next.js version detectedMonorepo Root DirectorySettings → Build and Deployment → Root Directory

Step 3: Pull the full log from the CLI when the UI truncates

The dashboard log viewer can scroll slowly and collapses sections. The CLI is faster for grepping:

# Stream/inspect logs for a specific deployment
vercel inspect <deployment-url> --logs

# Reproduce locally with the same builders Vercel uses, verbose
vercel build --debug

Step 4: Test the fix with Redeploy, not a fresh commit

When you’re testing a config-only fix (env var, Node version, Root Directory), use Redeploy in the dashboard instead of pushing a new commit. To force a clean build, uncheck Use existing Build Cache in the Redeploy dialog. Other ways to bypass the cache:

  • CLI: vercel --force
  • Env var: set VERCEL_FORCE_NO_BUILD_CACHE = 1 on the project

(The build cache is capped at 1 GB per key and kept for one month, so a stale cache is occasionally the culprit on its own.) Once a redeploy passes, commit the permanent fix to your repo.

How to confirm it’s fixed

A green checkmark on the deployment is necessary but not sufficient. Confirm all three:

  1. The deployment status reads Ready, not Error.
  2. The build log ends with Build Completed and a successful upload, with no error lines you skipped.
  3. The deployed URL actually renders — a passing build can still ship a blank page if an env var is wrong at runtime. See Static site renders a blank page if it does.

Prevention

  • Pin engines.node in package.json to match the dashboard’s Node.js Version.
  • Reproduce CI locally with nvm use + npm ci + npm run build — never npm install or npm run dev for reproduction.
  • Add every new env var to the right scope immediately (keep All Environments on unless you genuinely need different values).
  • Run npm run build (or tsc --noEmit + eslint) in a pre-push hook so type and lint errors surface before they reach Vercel.
  • Periodically build in a Linux container (Docker or GitHub Actions) to catch case-sensitivity and native-module issues macOS hides.
  • Document filename casing in CONTRIBUTING.md: components PascalCase, routes lowercase, imports match exactly.

FAQ

What does exited with 137 mean on Vercel? It’s an out-of-memory kill. The build process exceeded the container’s 8192 MB and the kernel sent it SIGKILL. Add NODE_OPTIONS=--max-old-space-size=6144 to the build, and if that isn’t enough, reduce build memory pressure or enable Enhanced Builds (16 GB) on Pro/Enterprise.

Why does my build pass locally but fail on Vercel? Three usual reasons: a different Node version (Vercel defaults to Node 24.x as of June 2026), filename casing that macOS ignores but Linux enforces, or an env var that exists locally but isn’t set in the Production scope. Reproduce with npm ci && npm run build on the same Node version to surface it.

How do I change the Node version Vercel uses? Dashboard: Settings → Build and Deployment → Node.js Version. Or commit "engines": { "node": "22.x" } in package.json, which overrides the dashboard setting and keeps it in version control.

The fix worked on Redeploy but the next git push fails again — why? Redeploy reuses the previous deployment’s settings and source. If you changed something only in the dashboard (an env var, the Node version) and didn’t commit the equivalent change to the repo, the next push builds from old source. Commit the package.json / config change too.

How do I see the full build log instead of the truncated dashboard view? Use vercel inspect <deployment-url> --logs from the CLI, or open the deployment, expand the Building step, and use the browser’s Find to jump between error lines.

For Vercel’s own reference, see the Troubleshooting Build Errors docs and the SIGKILL / Out of Memory guide.

Tags: #Vercel #Hosting #Build error #Debug

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