Error map

WARNING you have Transparent Huge Pages (THP) support enabled Redis: # WARNING you have Transparent Huge Pages (THP) support enabled in your kernel. This will create latency and memory usage issues with Redis

Redis · layer 5, Data

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Centre: this error. First ring: errors it is linked with (8). 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.

WARNING you have Transparent Huge Pages (THP) support enabled — Redis: # WARNING you have Transparent Huge Pages (THP) support enabled in your kernel. This will create latency and memory usage issues with Redis (Redis)WARNING you…Client output buffer limit reached (scheduled to be closed) — Redis: Client id=12 addr=10.0.0.5:51234 scheduled to be closed ASAP for overcoming of output buffer limits (Redis)Client output buffe…mem_fragmentation_ratio high / memory not released — Redis: INFO memory — mem_fragmentation_ratio:2.8 (RSS much larger than used_memory) (Redis)mem_fragmentation_r…BUSY Redis is busy running a script — Redis: (error) BUSY Redis is busy running a script. You can only call SCRIPT KILL or SHUTDOWN NOSAVE (Redis)BUSY Redis is busy …Celery with Redis: tasks run twice (visibility_timeout) — Celery: Task executed twice / Restoring unacked messages — Redis broker visibility_timeout shorter than task ETA (Redis)Celery with Redis: …BullMQ: Missing lock for job / job stalled more than allowable limit — BullMQ: Error: Missing lock for job 42. moveToFinished / job stalled more than allowable limit (Redis)BullMQ: Missing loc…WARNING: The TCP backlog setting of 511 cannot be enforced — Redis: # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128 (Redis)WARNING: The TCP ba…Redis::CannotConnectError (Sidekiq/Rails) — Redis::CannotConnectError: Error connecting to Redis on localhost:6379 (Errno::ECONNREFUSED) (Ruby / Rails)Redis::CannotConnec…WARNING: /sys/kernel/mm/transparent_hugepage/enabled is 'always' — MongoDB startup: WARNING: /sys/kernel/mm/transparent_hugepage/enabled is 'always'. We suggest setting it to 'never' (MongoDB)WARNING: /sys/kerne…OOMKilled — Kubernetes: OOMKilled (exit code 137) (Kubernetes)OOMKilledOutOfMemoryError — java.lang.OutOfMemoryError: Java heap space (Java)OutOfMemoryErrorSIGSEGV — Segmentation fault (core dumped) (Linux)SIGSEGVOOM command not allowed — Redis: OOM command not allowed when used memory > 'maxmemory' (Redis)OOM command not all…Keys disappear: maxmemory eviction (allkeys-lru) — Redis: evicted_keys growing — keys vanish unexpectedly because maxmemory is reached and a volatile/allkeys eviction policy is active (Redis)Keys disappear: max…Can't save in background: fork: Cannot allocate memory — Redis: # Can't save in background: fork: Cannot allocate memory / WARNING overcommit_memory is set to 0! (Redis)Can't save in backg…NOAUTH — ReplyError: NOAUTH Authentication required. (Node.js)NOAUTHWRONGTYPE — WRONGTYPE Operation against a key holding the wrong kind of value (Node.js)WRONGTYPEDENIED Redis is running in protected mode — Redis: DENIED Redis is running in protected mode because protected mode is enabled and no password is set for the default user (Redis)DENIED Redis is run…Error: connect ECONNREFUSED 127.0.0.1:6379 — Redis: Error: connect ECONNREFUSED 127.0.0.1:6379 / Could not connect to Redis at 127.0.0.1:6379: Connection refused (Redis)Error: connect ECON…NOAUTH / WRONGPASS invalid username-password pair — Redis: (error) NOAUTH Authentication required. / WRONGPASS invalid username-password pair or user is disabled (Redis)NOAUTH / WRONGPASS …ECONNRESET / Connection reset by peer on idle Redis connection — Redis: Error: read ECONNRESET / redis.exceptions.ConnectionError: Connection reset by peer after idle time (Redis)ECONNRESET / Connec…MaxAttemptsExceededException (queue job) — Laravel Queue: Illuminate\Queue\MaxAttemptsExceededException: App\Jobs\SendReport has been attempted too many times or run too long (Laravel)MaxAttemptsExceeded…Redis TLS: SSL handshake error / protocol mismatch — Redis: Error: write EPROTO ... SSL routines:ssl3_get_record:wrong version number / Connection reset by peer (TLS vs plaintext) (Redis)Redis TLS: SSL hand…ERR max number of clients reached — Redis: ERR max number of clients reached (Redis)ERR max number of c…Kernel panic - VFS: Unable to mount root fs — Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0) (Linux)Kernel panic - VFS:…Redis connection refused (Laravel) — Laravel: Predis\Connection\ConnectionException: Connection refused [tcp://127.0.0.1:6379] / RedisException: Connection refused (Laravel)Redis connection re…Can't connect to Redis from another host (bind 127.0.0.1) — Redis: Could not connect to Redis at 10.0.0.5:6379: Connection timed out (Redis)Can't connect to Re…Redis closes idle clients (timeout setting) — Redis: Closing idle client / Connection closed by server after timeout 300 (Redis)Redis closes idle c…MongoDB Atlas: connection timed out — IP not whitelisted — 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 (MongoDB)MongoDB Atlas: conn…Atlas: bad auth: Authentication failed — MongoServerError: bad auth : Authentication failed. (Atlas user / special characters in password) (MongoDB)Atlas: bad auth: Au…WiredTiger: No space left on device — MongoDB: WiredTiger error (28) [...] No space left on device / Fatal assertion 28558 ... disk full (MongoDB)WiredTiger: No spac…

Directly related (8)

Client output buffer limit reached (scheduled to be closed)Redis

Redis: Client id=12 addr=10.0.0.5:51234 scheduled to be closed ASAP for overcoming of output buffer limits

A client (often a slow subscriber or a replica) couldn't read data fast enough, so Redis disconnected it to protect memory.

mem_fragmentation_ratio high / memory not releasedRedis

Redis: INFO memory — mem_fragmentation_ratio:2.8 (RSS much larger than used_memory)

The process uses far more RSS than the data size, due to allocator fragmentation or deleted-but-not-returned memory.

BUSY Redis is busy running a scriptRedis

Redis: (error) BUSY Redis is busy running a script. You can only call SCRIPT KILL or SHUTDOWN NOSAVE

A long-running Lua script (or function) blocks the single-threaded server, so other commands are rejected.

Celery with Redis: tasks run twice (visibility_timeout)Redis

Celery: Task executed twice / Restoring unacked messages — Redis broker visibility_timeout shorter than task ETA

Celery's Redis transport redelivers a task if it isn't acknowledged within `visibility_timeout` (1 hour by default).

BullMQ: Missing lock for job / job stalled more than allowable limitRedis

BullMQ: Error: Missing lock for job 42. moveToFinished / job stalled more than allowable limit

A BullMQ worker lost the lock on a job (it took too long or the event loop was blocked), so the job is considered stalled.

WARNING: The TCP backlog setting of 511 cannot be enforcedRedis

Redis: # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128

The kernel limits the listen queue below Redis' `tcp-backlog`, so bursts of new connections may be dropped.

Redis::CannotConnectError (Sidekiq/Rails)Ruby / Rails

Redis::CannotConnectError: Error connecting to Redis on localhost:6379 (Errno::ECONNREFUSED)

Sidekiq or the Rails Redis cache/cable couldn't connect to Redis.

WARNING: /sys/kernel/mm/transparent_hugepage/enabled is 'always'MongoDB

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).

Two steps away (22)

OOMKilledKubernetes

Kubernetes: OOMKilled (exit code 137)

The container used more memory than its limit, and the kernel killed it.

OutOfMemoryErrorJava

java.lang.OutOfMemoryError: Java heap space

The JVM ran out of heap memory and garbage collection couldn’t free enough.

SIGSEGVLinux

Segmentation fault (core dumped)

A program accessed memory it wasn’t allowed to, and the kernel killed it with SIGSEGV (exit code 139).

OOM command not allowedRedis

Redis: OOM command not allowed when used memory > 'maxmemory'

Redis reached its maxmemory limit and the eviction policy (noeviction) refuses new writes.

Keys disappear: maxmemory eviction (allkeys-lru)Redis

Redis: evicted_keys growing — keys vanish unexpectedly because maxmemory is reached and a volatile/allkeys eviction policy is active

Redis removed keys to stay under `maxmemory` according to the eviction policy.

Can't save in background: fork: Cannot allocate memoryRedis

Redis: # Can't save in background: fork: Cannot allocate memory / WARNING overcommit_memory is set to 0!

Redis couldn't fork to write an RDB/AOF snapshot because the OS refused to allocate memory.

NOAUTHNode.js

ReplyError: NOAUTH Authentication required.

The Redis server requires a password (or ACL user) but the client didn’t authenticate.

WRONGTYPENode.js

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).

DENIED Redis is running in protected modeRedis

Redis: DENIED Redis is running in protected mode because protected mode is enabled and no password is set for the default user

Redis refuses connections from non-local clients when it has no password and is bound to all interfaces.

Error: connect ECONNREFUSED 127.0.0.1:6379Redis

Redis: Error: connect ECONNREFUSED 127.0.0.1:6379 / Could not connect to Redis at 127.0.0.1:6379: Connection refused

Nothing is listening on the Redis host/port your client uses.

NOAUTH / WRONGPASS invalid username-password pairRedis

Redis: (error) NOAUTH Authentication required. / WRONGPASS invalid username-password pair or user is disabled

The server requires a password (or ACL user) and the client sent none or the wrong one.

ECONNRESET / Connection reset by peer on idle Redis connectionRedis

Redis: Error: read ECONNRESET / redis.exceptions.ConnectionError: Connection reset by peer after idle time

A middlebox or Redis closed an idle connection, and the pooled client reused it.

MaxAttemptsExceededException (queue job)Laravel

Laravel Queue: Illuminate\Queue\MaxAttemptsExceededException: App\Jobs\SendReport has been attempted too many times or run too long

A queued job failed repeatedly or ran past its timeout, so it was marked failed.

Redis TLS: SSL handshake error / protocol mismatchRedis

Redis: Error: write EPROTO ... SSL routines:ssl3_get_record:wrong version number / Connection reset by peer (TLS vs plaintext)

The client and server disagree about TLS — plaintext client to a TLS port, or TLS client to a plaintext port.

ERR max number of clients reachedRedis

Redis: ERR max number of clients reached

Redis hit its `maxclients` limit (default 10000, lower if the OS limit is low), so new connections are refused.

Kernel panic - VFS: Unable to mount root fsLinux

Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)

The kernel booted but couldn’t mount the root filesystem — usually a missing or broken initramfs after a kernel update.

Redis connection refused (Laravel)Laravel

Laravel: Predis\Connection\ConnectionException: Connection refused [tcp://127.0.0.1:6379] / RedisException: Connection refused

Laravel can't connect to Redis, which it uses for cache, sessions or queues.

Can't connect to Redis from another host (bind 127.0.0.1)Redis

Redis: Could not connect to Redis at 10.0.0.5:6379: Connection timed out

Redis only listens on localhost by default, so remote clients time out or are refused.

Redis closes idle clients (timeout setting)Redis

Redis: Closing idle client / Connection closed by server after timeout 300

Redis' `timeout` directive closes connections idle longer than N seconds.

MongoDB Atlas: connection timed out — IP not whitelistedMongoDB

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.

Atlas: bad auth: Authentication failedMongoDB

MongoServerError: bad auth : Authentication failed. (Atlas user / special characters in password)

Atlas rejected the username/password in the connection string.

WiredTiger: No space left on deviceMongoDB

MongoDB: WiredTiger error (28) [...] No space left on device / Fatal assertion 28558 ... disk full

MongoDB ran out of disk space on the data volume and stopped or refuses writes.