Error map
Index key too large to index MongoServerError: Index key too large to index (key size exceeds 1024 bytes) / pre-4.2 behaviour
MongoDB · layer 5, Data
Centre: this error. First ring: errors it is linked with (11). Outer ring: what those are linked with. Colours show the layer of a request each error belongs to. Click any dot to re-centre the map on it; hover to follow its connections. The centre dot opens the error page.
Directly related (11)
Lambda: Request must be smaller than 6291456 bytes for the InvokeFunction operation (RequestEntityTooLargeException)
The event payload (or response) is over Lambda’s 6 MB synchronous limit (256 KB for async invocations).
Lambda: Unzipped size must be smaller than 262144000 bytes
The function code plus layers exceed Lambda’s 250 MB unzipped limit for zip deployments.
fork: retry: Resource temporarily unavailable (process/thread limit)
The user or container hit its maximum number of processes/threads (ulimit -u, pids cgroup), so new processes can’t be created.
Too many open files (EMFILE)
The process hit its file-descriptor limit — sockets, files and pipes all count.
MongoServerError: E11000 duplicate key error collection: db.users index: email_1 dup key
An insert/update violated a unique index in MongoDB.
MongoServerSelectionError: Could not connect to any servers in your MongoDB Atlas cluster. One common reason is that you're trying to access the database from an IP that isn't whitelisted
Atlas rejects connections from IP addresses that aren't in the project's Network Access list.
MongoServerError: bad auth : Authentication failed. (Atlas user / special characters in password)
Atlas rejected the username/password in the connection string.
MongoServerError: Exceeded memory limit for $group, but didn't allow external sort. Pass allowDiskUse:true to opt in
An aggregation stage needed more than 100 MB of RAM and spilling to disk wasn't enabled.
MongoServerError: BSONObj size: 17825792 (0x1100000) is invalid. Size must be between 0 and 16793600(16MB)
A single document (or an aggregation result row) grew past MongoDB's 16 MB limit.
MongoDB: WARNING: soft rlimits too low. Number of files is 1024, should be at least 64000 / Too many open files
The OS file-descriptor limit for `mongod` is too low, causing connection or file errors under load.
MongoServerError: Index build failed: E11000 duplicate key error collection: db.users index: email_1 dup key
You tried to build a unique index but existing documents already contain duplicate values.
Two steps away (32)
HTTP 413 Content Too Large (Request Entity Too Large)
The request body is bigger than the server is willing to accept — usually a file upload over the configured limit.
AWS Lambda: Task timed out after X seconds
The function ran longer than its configured timeout (default 3 seconds) and Lambda stopped it.
Runtime.ImportModuleError: Unable to import module 'lambda_function': No module named 'x'
Lambda couldn’t load your handler file or one of its dependencies — the package is missing from the deployment zip/layer or the h…
Runtime.HandlerNotFound: index.handler is undefined or not exported
Lambda loaded the file but couldn’t find the function named in the handler setting.
Lambda: Runtime exited with error: signal: killed (Runtime.ExitError)
The function process was killed — almost always because it ran out of its configured memory.
InvalidParameterValueException: The role defined for the function cannot be assumed by Lambda
The execution role’s trust policy doesn’t allow lambda.amazonaws.com — or the role was just created and IAM hasn’t propagated yet.
Error: listen EADDRINUSE: address already in use :::3000
Another process is already listening on that port.
Error: write EPIPE
Node wrote to a pipe or socket whose other end was already closed.
RangeError [ERR_CHILD_PROCESS_STDIO_MAXBUFFER]: stdout maxBuffer length exceeded
child_process.exec/execSync produced more output than its buffer allows (default 1 MB).
Error: ENOENT: no such file or directory
A file or directory the program tried to open doesn’t exist at that path.
Error: socket hang up / read ECONNRESET
The other side closed the TCP connection abruptly while your client was still using it.
MySQL ERROR 1040 (08004): Too many connections
MySQL reached `max_connections` and refuses new clients.
MySQL ERROR 1062 (23000): Duplicate entry for key
An INSERT/UPDATE would create a duplicate value in a PRIMARY or UNIQUE key.
PostgreSQL: ERROR: duplicate key value violates unique constraint
An INSERT/UPDATE would create a duplicate in a UNIQUE or PRIMARY KEY column — or the id sequence is behind the existing data.
MongooseError: Operation `users.find()` buffering timed out after 10000ms
Mongoose queued a query waiting for a connection that never opened.
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.
Error [ERR_STREAM_PREMATURE_CLOSE]: Premature close
A stream ended or was destroyed before it finished — often a client disconnect or upstream aborting a download.
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.
MongooseServerSelectionError: connect ECONNREFUSED 127.0.0.1:27017
The MongoDB driver couldn’t find a reachable server for the connection string.
ReplyError: NOAUTH Authentication required.
The Redis server requires a password (or ACL user) but the client didn’t authenticate.
denied: Your authorization token has expired. Reauthenticate and try again. (Amazon ECR)
Docker’s login to Amazon ECR has expired — ECR tokens last 12 hours, so pushes and pulls fail until you log in again.
Kubernetes: OOMKilled (exit code 137)
The container used more memory than its limit, and the kernel killed it.
Segmentation fault (core dumped)
A program accessed memory it wasn’t allowed to, and the kernel killed it with SIGSEGV (exit code 139).
Killed / Out of memory: Killed process (Linux OOM killer)
The kernel ran out of memory and killed a process to recover — the program just prints “Killed” (exit code 137).
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.
ValidationError: User validation failed: email: Path `email` is required.
A document failed Mongoose schema validation before saving.
MongoDB: MongoServerError: Document failed validation (code 121)
The collection has a JSON Schema validator and the inserted/updated document doesn’t satisfy it.
mongod: Process exited with status 14 — Exception in initAndListen: IllegalOperation: Attempted to create a lock file on a read-only directory
`mongod` couldn't start because the data directory or log/socket file isn't writable or already locked.
MongoDB: Out of memory: Killed process (mongod) — WiredTiger cache + queries exhausted RAM
The Linux OOM killer terminated `mongod` because the host ran out of memory.
MongoDB startup: WARNING: /sys/kernel/mm/transparent_hugepage/enabled is 'always'. We suggest setting it to 'never'
Transparent Huge Pages are enabled, which can hurt MongoDB performance (latency spikes).
MongoServerError: Executor error during find command :: caused by :: Sort exceeded memory limit of 104857600 bytes, but did not opt in to external sorting
A `find().sort()` without a supporting index had to sort too much data in memory.
mongorestore: Failed: db.coll: error restoring from dump: E11000 duplicate key error / unsupported BSON version
`mongorestore` couldn't load some documents — they already exist, indexes conflict, or the dump/server versions don't match.
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