| req.body undefined |
Express: req.body is undefined / {} (body parser missing) |
Express didn’t parse the request body because no body-parsing middleware matched the request’s Content-Type. |
| nodemon crashed |
[nodemon] app crashed - waiting for file changes before starting... |
Your app threw an error on startup; nodemon is waiting for a file change to retry. |
| CastError ObjectId |
CastError: Cast to ObjectId failed for value "x" (type string) at path "_id" |
A value that isn’t a valid 24-hex-character ObjectId was used in an _id query. |
| DEP0005 |
DeprecationWarning: Buffer() is deprecated due to security and usability issues (DEP0005) |
Code (yours or a dependency) uses the deprecated new Buffer() constructor. |
| DEP0040 |
DeprecationWarning: The `punycode` module is deprecated (DEP0040) |
A dependency imports Node’s built-in punycode module, deprecated since Node 21. |
| ERR_HTTP_HEADERS_SENT |
Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client |
An Express/Node handler tried to send a second response (or set headers) after one was already sent. |
| ERR_PACKAGE_PATH_NOT_EXPORTED |
Error [ERR_PACKAGE_PATH_NOT_EXPORTED]: Package subpath './x' is not defined by "exports" |
You imported a deep path inside a package that its package.json "exports" field doesn’t expose. |
| ERR_REQUIRE_ESM |
Error [ERR_REQUIRE_ESM]: require() of ES Module not supported |
CommonJS code used `require()` on a package that is ES-module-only (node-fetch 3, chalk 5, nanoid 4, got 12…). |
| ERR_STREAM_PREMATURE_CLOSE |
Error [ERR_STREAM_PREMATURE_CLOSE]: Premature close |
A stream ended or was destroyed before it finished — often a client disconnect or upstream aborting a downloa… |
| ERR_TLS_CERT_ALTNAME_INVALID |
Error [ERR_TLS_CERT_ALTNAME_INVALID]: Hostname/IP does not match certificate's altnames |
The server’s certificate doesn’t cover the hostname you connected to. |
| prisma generate |
Error: @prisma/client did not initialize yet. Please run "prisma generate" |
The generated Prisma Client is missing or out of date. |
| MODULE_NOT_FOUND |
Error: Cannot find module 'x' (MODULE_NOT_FOUND) |
Node can’t resolve the module path — the package isn’t installed, or a relative path/extension is wrong. |
| ECONNREFUSED |
Error: connect ECONNREFUSED 127.0.0.1:5432 |
Nothing is listening at that host:port — the target service is down or you’re connecting to the wrong address. |
| EEXIST |
Error: EEXIST: file already exists, mkdir |
Node tried to create a file/directory/symlink that already exists. |
| EISDIR |
Error: EISDIR: illegal operation on a directory, read |
A file API (readFile, writeFile, createReadStream) was given a directory path. |
| ENOENT |
Error: ENOENT: no such file or directory |
A file or directory the program tried to open doesn’t exist at that path. |
| ENOTDIR |
Error: ENOTDIR: not a directory |
A path treats a file as if it were a directory (e.g. file.txt/child). |
| EPERM |
Error: EPERM: operation not permitted, rename / unlink |
The OS refused a file operation — on Windows usually because another process (antivirus, editor, indexer) has… |
| ERR_OSSL_EVP_UNSUPPORTED |
Error: error:0308010C:digital envelope routines::unsupported |
An old build tool (webpack 4, old react-scripts) uses a hash algorithm that OpenSSL 3 in Node 17+ disables. |
| listen EACCES |
Error: listen EACCES: permission denied 0.0.0.0:80 |
Node isn’t allowed to bind that port — ports below 1024 need root on Linux/macOS, and some Windows ports are… |
| EADDRINUSE |
Error: listen EADDRINUSE: address already in use :::3000 |
Another process is already listening on that port. |
| node-sass |
Error: Node Sass does not yet support your current environment |
node-sass (deprecated) has no binary for your Node version/OS. |
| Prisma P1001 |
Error: P1001: Can't reach database server at `host`:`5432` |
Prisma couldn’t connect to the database in DATABASE_URL. |
| spawn EACCES |
Error: spawn EACCES |
Node tried to execute a file that isn’t executable (missing +x permission) or isn’t a program. |
| Unhandled 'error' event |
Error: Unhandled 'error' event (events.js / node:events) |
An EventEmitter (stream, socket, child process, server) emitted 'error' and nothing listened for it, so Node… |
| EPIPE |
Error: write EPIPE |
Node wrote to a pipe or socket whose other end was already closed. |
| heap out of memory |
FATAL ERROR: Reached heap limit Allocation failed - JavaScript heap out of memory |
The V8 heap hit its limit — a large build (webpack, tsc, Next.js) needs more memory, or the app leaks. |
| MaxListenersExceededWarning |
MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 listeners added |
More than 10 listeners were added to one event — often a leak where listeners are added repeatedly. |
| buffering timed out |
MongooseError: Operation `users.find()` buffering timed out after 10000ms |
Mongoose queued a query waiting for a connection that never opened. |
| MongoServerSelectionError |
MongooseServerSelectionError: connect ECONNREFUSED 127.0.0.1:27017 |
The MongoDB driver couldn’t find a reachable server for the connection string. |
| E11000 duplicate key |
MongoServerError: E11000 duplicate key error collection: db.users index: email_1 dup key |
An insert/update violated a unique index in MongoDB. |
| UnhandledPromiseRejection |
Node.js: [UnhandledPromiseRejection] — This error originated either by throwing inside of an async function without a catch block |
A promise rejected and nothing handled it; since Node 15 this crashes the process. |
| EBADENGINE |
npm WARN EBADENGINE Unsupported engine / The engine "node" is incompatible with this module |
A package requires a different Node.js version than the one you’re running. |
| Prisma P2002 |
PrismaClientKnownRequestError P2002: Unique constraint failed on the fields: (`email`) |
A Prisma create/update violated a unique constraint. |
| maxBuffer exceeded |
RangeError [ERR_CHILD_PROCESS_STDIO_MAXBUFFER]: stdout maxBuffer length exceeded |
child_process.exec/execSync produced more output than its buffer allows (default 1 MB). |
| NOAUTH |
ReplyError: NOAUTH Authentication required. |
The Redis server requires a password (or ACL user) but the client didn’t authenticate. |
| SequelizeConnectionRefusedError |
SequelizeConnectionRefusedError: connect ECONNREFUSED 127.0.0.1:5432 |
Sequelize couldn’t connect to the database server. |
| SyntaxError import |
SyntaxError: Cannot use import statement outside a module |
An `import` statement ran in a context treated as CommonJS (Node without "type": "module", a browser script w… |
| TS2532 / TS18048 |
TS18048: 'x' is possibly 'undefined'. (TS2532: Object is possibly 'undefined'.) |
TypeScript requires you to handle the case where a value may be undefined before using it. |
| TS2304 |
TS2304: Cannot find name 'x'. |
TypeScript doesn’t know an identifier — a missing import, missing type definitions (e.g. for Node or Jest glo… |
| TS2307 |
TS2307: Cannot find module 'x' or its corresponding type declarations. |
TypeScript can’t resolve the import — the package isn’t installed, the path alias isn’t configured, or there… |
| TS2339 |
TS2339: Property 'x' does not exist on type 'Y'. |
TypeScript’s type for the object doesn’t include that property. |
| TS2345 |
TS2345: Argument of type 'string | undefined' is not assignable to parameter of type 'string'. |
A value’s type doesn’t match the function parameter — commonly a possibly-undefined value passed where a defi… |
| TS7016 |
TS7016: Could not find a declaration file for module 'x'. 'x.js' implicitly has an 'any' type. |
The JavaScript package has no TypeScript types bundled and no @types package installed. |
| ERR_IMPORT_ATTRIBUTE_MISSING |
TypeError [ERR_IMPORT_ATTRIBUTE_MISSING]: Module needs an import attribute of "type: json" |
An ES module imported a .json file without the required import attribute. |
| ERR_INVALID_ARG_TYPE |
TypeError [ERR_INVALID_ARG_TYPE]: The "path" argument must be of type string. Received undefined |
A Node API got an argument of the wrong type — usually undefined because an env var or config value is missin… |
| ERR_UNKNOWN_FILE_EXTENSION |
TypeError [ERR_UNKNOWN_FILE_EXTENSION]: Unknown file extension ".ts" |
Node tried to run a TypeScript file as ESM without a TypeScript loader. |
| fetch failed |
TypeError: fetch failed (cause: ConnectTimeoutError / ECONNREFUSED / UND_ERR) |
Node’s built-in fetch (undici) couldn’t complete the request; the real reason is in error.cause. |
| path-to-regexp |
TypeError: Missing parameter name at 1 (path-to-regexp) |
An Express 5 (path-to-regexp v8) route uses old wildcard syntax like '*' or '/:id?'. |
| Router.use middleware |
TypeError: Router.use() requires a middleware function but got a Object |
app.use()/router.use() received an object instead of a function — usually a router module that wasn’t exporte… |
| Mongoose ValidationError |
ValidationError: User validation failed: email: Path `email` is required. |
A document failed Mongoose schema validation before saving. |
| WRONGTYPE |
WRONGTYPE Operation against a key holding the wrong kind of value |
A Redis command was used on a key of a different type (e.g. HGET on a string key). |