CodeWithLogs / Diagnostic workbench

Developer Error Decoder

Start with the error you can see. Match a known signature, understand its limits, and work through the next diagnostic steps without sending your log to an AI service.

Client-side analysisNo account requiredNo AI serviceNo script execution

How to read an error without guessing

Start at the first actionable error. A final “build exited with 1” message often hides the useful line above it.
Keep the code, failed operation and framework context. Redact secrets and identifying paths before pasting.
Compare the suggested checks with your OS, shell and dependency versions. Change one thing, then repeat the failing operation and the project’s tests.

This decoder uses fixed rules; it cannot inspect your machine, read your repository, resolve dependencies or prove a root cause. Multiple signatures can match the same log. Unknown messages get an unsupported result instead of an invented explanation. Input is limited to 20,000 characters, terminal styling is normalized, and pasted markup is never rendered as HTML.

Matching tests check these rules, not every suggested repair. Evidence from local fixtures is scoped in each result. Current setup fixtures ran on Windows 10, not Windows 11. No screenshots, live Vercel repair or browser hydration fix are claimed.

Supported errors and first checks

These references are readable without using the tool. Open a signature to compare its example and diagnostic scope with your log.

npm ERESOLVE: dependency resolution conflict

npm error code ERESOLVE
npm error ERESOLVE unable to resolve dependency tree

npm could not construct the requested dependency tree. A conflicting peer requirement is one common reason; read the conflicting package names and ranges in the full log.

First check: Find the Found, Could not resolve dependency and peer lines. Record both versions and the required range.

Limits: npm 7+ installs enforce peer requirements by default. The local Phase 3 fixture reproduced a conflict and a compatible-version repair with npm 10.9.3; that does not prove your dependency set is compatible. npm ls can exit nonzero when the tree is invalid.

npm peer dependency configuration

npm EPERM: an operation was not permitted

npm error code EPERM
npm error syscall rename

The operating system refused a filesystem operation. EPERM alone does not identify the responsible process, permission or security policy.

First check: Read the syscall and path lines; distinguish the project directory from the npm cache or a global install.

Limits: Filesystem checks only. This decoder cannot inspect locks, ACLs, antivirus or your disk. These EPERM remedies have not been reproduced in the local fixtures.

Node.js system error definitions

PowerShell blocked the npm.ps1 launcher

npm.ps1 cannot be loaded because running scripts is disabled on this system.

PowerShell selected a script launcher that the effective execution policy did not allow. This differs from Node not being installed or a failed npm install.

First check: Inspect launcher resolution and the effective policies in the failing shell.

Limits: PowerShell on Windows. A Restricted child-process case and explicit npm.cmd invocation passed on Windows 10 / PowerShell 7.6.5 / npm 10.9.3. Windows 11 and managed-policy cases remain untested.

Microsoft: PowerShell execution policies

The shell cannot resolve the node command

'node' is not recognized as an internal or external command, operable program or batch file.

The current shell cannot find the requested command. That does not establish whether Node is absent, installed elsewhere or hidden by a stale PATH.

First check: In PowerShell, check all command matches and the executable search path.

Limits: Windows shell lookup. A process-only missing/restored PATH case passed on Windows 10 with Node 22.18.0. Installer repair and Windows 11 behavior were not tested.

Microsoft: Node.js development on Windows

The shell cannot resolve the git command

git: The term 'git' is not recognized as a name of a cmdlet, function, script file, or executable program.

Git did not start because the shell could not resolve its command. Repository contents and credentials are not the initial cause of a command lookup failure.

First check: Inspect command resolution in the failing PowerShell session.

Limits: A process-only missing/restored PATH case passed on Windows 10 with Git 2.55.0.windows.4. Windows Terminal UI, installer repair and Windows 11 were not tested.

Git: Windows installation options

React / Next.js hydration mismatch

Hydration failed because the server rendered HTML didn't match the client.

The server-rendered HTML and the client's initial render disagree. The message identifies the mismatch, not which component caused it.

First check: Use the component stack and HTML diff to locate the first differing output.

Limits: React hydration guidance applicable to Next.js. This pattern is not proof that the log came from Next.js. No browser mismatch/fix has been verified in the local fixtures.

Next.js: hydration errors

Module resolution failure: Next.js checklist

Module not found: Can't resolve '@/components/Status'

The resolver could not locate an imported module. A missing package is only one possibility; inspect the import trace and exact path first.

First check: Classify the import as a relative file, configured alias or installed package; check spelling and tracked filename case.

Limits: Module-not-found signatures also appear outside Next.js; this is a Next.js-oriented checklist. Local import/alias/type failure-and-repair fixtures passed on Next 16.2.6 / Windows 10; Linux casing behavior was not run.

Next.js: module not found

Vercel build or deployment failure

Vercel: Error: Command "npm run build" exited with 1

A build exit message summarizes failure; it usually is not the underlying error. A named Vercel platform error needs its own deployment context.

First check: In the failed deployment, locate the first actionable error above the final exit summary. Distinguish build logs from function invocation logs.

Limits: Matches explicit Vercel context with a build failure, or the listed platform codes. It cannot see a deployment, its settings, plan limits or logs. No Vercel deployment was tested locally.

Continue the investigation

For a dependency error, the package.json inspector can show declared ranges and script hooks. It does not replace npm’s resolver or a lockfile review.

Common Vercel deployment errors — existing article; unverified published version.
Debugging production errors in Next.js — existing article; unverified published version.
Next.js folder structure — existing article; unverified published version.

Read our evidence standard before treating an article as tested. Report an incorrect signature through Contact, using a minimal redacted example. Do not include tokens or customer data.

What happens to pasted errors?

The decoder keeps input only in this page’s current React state. Its analysis does not upload logs, persist them in storage or encode them in a share URL. Clear removes the input and displayed results; browsers can independently restore page state during navigation. Existing site analytics may still load; see the privacy policy. Clipboard access happens only when you choose Copy, and copies the static checklist rather than your original log.