Error map
rs.initiate failed: member not reachable / no host described in new configuration MongoDB: replSetInitiate quorum check failed: Could not connect to mongo2:27017 / No host described in new configuration 1 for replica set rs0 maps to this node
MongoDB · layer 5, Data
Centre: this error. First ring: errors it is linked with (12). 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 (12)
Failed to create pod sandbox: plugin type="calico" failed (add): ... (FailedCreatePodSandBox)
The kubelet couldn’t set up the pod’s network sandbox — almost always a CNI plugin problem or exhausted pod IPs.
spec.ports[0].nodePort: Invalid value: 80: provided port is not in the valid range. The range of valid ports is 30000-32767
A NodePort Service asked for a port outside the cluster’s NodePort range (default 30000–32767).
Error response from daemon: Pool overlaps with other one on this address space
Docker tried to create a network whose subnet clashes with an existing Docker network (or a VPN/host route).
driver failed programming external connectivity on endpoint: iptables: No chain/target/match by that name
Docker’s iptables rules were wiped (firewalld/ufw reload, iptables flush) while Docker was running, so it can’t publish ports.
Error response from daemon: network X not found
The container or Compose project refers to a Docker network that doesn’t exist (any more).
DNS not working inside a Kubernetes pod (could not resolve host / nslookup: can't resolve)
Pods can’t resolve service names or external hosts — CoreDNS is down, blocked by NetworkPolicy, or the upstream resolver fails.
Ingress returns "404 Not Found" / "default backend - 404" (ingress-nginx)
The ingress controller received the request but no Ingress rule matched the host/path, so it answered with its default backend.
Service has no endpoints (no endpoints available for service / Endpoints: <none>)
The Service’s selector matches no ready pods, so traffic to it is refused or returns 503.
ECS task stopped: CannotPullContainerError: pull image manifest has been retried ... / ref pull has been retried
The ECS task couldn’t pull its image — no network route to the registry, missing ECR permissions, or a wrong image tag.
MongoServerSelectionError: Could not find host matching read preference { mode: "secondary" } for set rs0
The requested read preference (secondary, nearest with tags) matches no available member.
MongoServerError: already initialized (rs.initiate on a configured replica set)
`rs.initiate()` was called on a node that already has a replica set configuration.
MongoDB: We are too stale to use X as a sync source / replSet too stale to catch up — member in RECOVERING state
A secondary fell so far behind that the primary's oplog no longer covers the gap, so it can't resync by replaying.
Two steps away (33)
Kubernetes: Pod Evicted — The node was low on resource: memory / ephemeral-storage
The kubelet removed the pod because its node ran short of memory or disk.
Kubernetes node NotReady (Kubelet stopped posting node status)
The control plane hasn’t heard from a node’s kubelet, or the kubelet reports a problem — pods there stop being scheduled and are…
android.os.NetworkOnMainThreadException
The app made a network call on the main (UI) thread, which Android forbids.
Job for nginx.service failed because the control process exited with error code
systemd tried to start the service, but its start command failed. The real reason is in the service’s status/journal.
Failed to start x.service: Unit x.service not found
systemd has no unit with that name — the package isn’t installed, the name differs on this distro, or a new unit file wasn’t load…
systemd: Start request repeated too quickly / service hit its start limit
The service crashed and restarted several times in a short period, so systemd stopped trying (StartLimitBurst).
docker compose: services.x Additional property y is not allowed / yaml: line N: mapping values are not allowed
The compose file is invalid YAML or uses a key Compose doesn’t recognise at that level (usually an indentation mistake).
docker-compose: command not found / 'compose' is not a docker command
Your system has only one of the two Compose flavours: the old docker-compose (v1) binary or the newer docker compose (v2) plugin.
service "web" depends on undefined service "db": invalid compose project
A service lists depends_on (or links/networks) for a service name that isn’t defined in the Compose file(s) being used.
Error: listen EADDRINUSE: address already in use :::3000
Another process is already listening on that port.
Docker: Bind for 0.0.0.0:80 failed: port is already allocated
Another container or host process already publishes that host port.
Cloudflare Error 1020: Access Denied
A Cloudflare firewall/WAF custom rule blocked the request — the visitor’s IP, country, user agent or request pattern matched a bl…
WARN: the attribute `version` is obsolete, it will be ignored
A harmless Compose v2 warning: the top-level version: line in docker-compose.yml is no longer used.
Docker container is unhealthy (health check failing)
The container is running, but its HEALTHCHECK command keeps failing, so Docker (and dependent services) consider it unhealthy.
HttpRequestException: No connection could be made because the target machine actively refused it (localhost:5001)
Nothing is listening on the host/port the client called — the API isn’t running, uses another port, or the container/network addr…
Error: getaddrinfo ENOTFOUND host / Name or service not known
DNS lookup for the hostname failed — the name is wrong, doesn’t exist, or this machine can’t resolve it.
net::ERR_NAME_NOT_RESOLVED (This site can't be reached — server IP address could not be found)
DNS couldn’t resolve the hostname in the browser.
cURL error 6: Could not resolve host: api.example.com
PHP cURL couldn’t resolve the hostname via DNS.
HTTP 404 Not Found
The server can’t find anything at the requested URL.
Error from server: admission webhook "validate.nginx.ingress.kubernetes.io" denied the request
A validating admission webhook (ingress-nginx, Gatekeeper/OPA, Kyverno) inspected your object and rejected it; the reason follows…
Error Domain=NSURLErrorDomain Code=-1001 "The request timed out."
The server didn’t respond within URLSession’s timeout (60 s default) — slow server, unreachable host on this network, or a stalle…
HTTP 503 Service Unavailable
The server is temporarily unable to handle the request — overloaded, in maintenance, or has no healthy backends.
Readiness probe failed: HTTP probe failed with statuscode: 503 / connect: connection refused
The container is running, but its readiness check fails, so the pod is marked not ready and removed from Service endpoints.
Windows Update error 0x80070422 (service is disabled)
Windows Update (or the Microsoft Store/Defender) can’t run because a required service — usually Windows Update (wuauserv) — is di…
Kubernetes: ImagePullBackOff / ErrImagePull
The node can’t pull the container image — wrong name/tag, missing registry credentials, or registry unreachable.
npm ERR! code EROFS — EROFS: read-only file system
npm tried to write to a read-only location (read-only container filesystem, mounted volume, or system path).
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.
MongoServerError: Transaction numbers are only allowed on a replica set member or mongos
You started a transaction (or used retryWrites) on a standalone MongoDB server, which doesn't support them.
MongoServerError: not primary and secondaryOk=false / NotWritablePrimary: not master
A write (or read without secondary preference) hit a secondary — the primary changed or you connected directly to a secondary.
MongoServerSelectionError: Server selection timed out after 30000 ms — topology type ReplicaSetNoPrimary
The driver sees the replica set members but none is a primary (election failing or members unreachable).
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.
MongoDB: Detected unclean shutdown - /var/lib/mongodb/mongod.lock is not empty
MongoDB wasn't shut down cleanly (crash/power loss), so it warns or refuses to start without recovery.
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.
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