# Common Kubernetes Error Messages
Quick reference for error messages and their solutions.
## Pod Errors
### CrashLoopBackOff
**Meaning:** Container keeps crashing and restarting.
**Causes:**
- Application crash on startup
- Missing configuration or secrets
- Resource exhaustion (OOM)
- Failing health checks
**Fix:**
```python
get_pod_logs(name, namespace, previous=True)
describe_pod(name, namespace)
```
### ImagePullBackOff / ErrImagePull
**Meaning:** Cannot pull container image.
**Causes:**
- Image doesn't exist
- Private registry without credentials
- Network issues
- Rate limiting (Docker Hub)
**Fix:**
```python
describe_pod(name, namespace)
```
### OOMKilled (Exit Code 137)
**Meaning:** Container exceeded memory limit.
**Causes:**
- Memory limit too low
- Memory leak in application
- Large data processing
**Fix:**
```python
get_pod_metrics(name, namespace)
```
### Exit Code 1
**Meaning:** Application error.
**Fix:** Check application logs for stack trace.
### Exit Code 127
**Meaning:** Command not found.
**Fix:** Check container image has required binaries.
### Exit Code 128+N
**Meaning:** Container killed by signal N.
| Exit Code | Signal | Meaning |
|-----------|--------|---------|
| 130 | SIGINT (2) | Interrupt |
| 137 | SIGKILL (9) | Killed (OOM) |
| 143 | SIGTERM (15) | Terminated |
## Scheduling Errors
### 0/N nodes are available
**Causes:**
- Insufficient resources
- Node selector/affinity not matching
- Taints without tolerations
- All nodes cordoned
**Fix:**
```python
describe_pod(name, namespace)
get_nodes()
```
### PodExceedsFreeCPU / PodExceedsFreeMemory
**Fix:** Reduce resource requests or add capacity.
### NodeNotReady
**Fix:**
```python
describe_node(name)
```
## Storage Errors
### PersistentVolumeClaim not found
**Fix:** Create the PVC before the pod.
### Unable to attach or mount volumes
**Causes:**
- PV already attached elsewhere
- Storage class misconfigured
- Node has no access to storage
**Fix:**
```python
describe_pvc(name, namespace)
get_storage_classes()
```
## Network Errors
### Connection refused
**Causes:**
- Service not exposed on expected port
- Application not listening
- Firewall/NetworkPolicy blocking
**Fix:**
```python
get_endpoints(namespace)
get_network_policies(namespace)
```
### No route to host
**Causes:**
- Node network issues
- CNI problems
**Fix:** Check CNI pods in kube-system.
### DNS resolution failed
**Fix:**
```python
get_pods(namespace="kube-system", label_selector="k8s-app=kube-dns")
```
## RBAC Errors
### Forbidden: User cannot...
**Causes:**
- Missing Role/ClusterRole
- Missing RoleBinding/ClusterRoleBinding
- ServiceAccount not assigned
**Fix:**
```python
get_cluster_roles()
get_role_bindings(namespace)
```
## Admission Controller Errors
### Admission webhook denied
**Causes:**
- Policy violation (Kyverno/Gatekeeper)
- Webhook unavailable
**Fix:**
```python
kyverno_clusterpolicies_list_tool()
gatekeeper_constraints_list_tool()
```
## Resource Limit Errors
### Forbidden: exceeded quota
**Fix:**
```python
get_resource_quotas(namespace)
```
### LimitRange rejection
**Fix:** Adjust resource requests/limits to match LimitRange.
## Probe Failures
### Liveness probe failed
**Meaning:** Container will be restarted.
### Readiness probe failed
**Meaning:** Pod removed from service endpoints.
**Common causes:**
- Wrong port in probe config
- Application slow to start
- Dependencies unavailable
**Fix:**
```python
describe_pod(name, namespace)
get_pod_logs(name, namespace)
```
## Quick Lookup
| Error | First Tool |
|-------|------------|
| CrashLoopBackOff | `get_pod_logs(previous=True)` |
| ImagePullBackOff | `describe_pod` |
| Pending (scheduling) | `describe_pod`, `get_events` |
| PVC Pending | `describe_pvc` |
| Connection refused | `get_endpoints` |
| RBAC Forbidden | `get_role_bindings` |
