OpenStack Troubleshooting Toolkit
Use this OpenStack troubleshooting toolkit to diagnose 504 gateway timeouts, Cinder scheduler and RabbitMQ RPC timeouts, dead Neutron agents, Keystone auth failures, and Kolla-Ansible control-plane problems.
Paste your error and get a triage plan.
Paste a log line, CLI error, stack trace, service failure, or config snippet and get a structured troubleshooting plan. Your snippet is carried straight into the AI Incident Response Assistant with OpenStack context prefilled.
Do not paste secrets, tokens, private keys, passwords, or customer data. Your snippet stays in your browser until you open the assistant.
Top 25 OpenStack Errors and Failure Modes
The production failures engineers hit most — each links to a full cause → fix → prevention guide.
OpenStack 504 Gateway Timeout
HAProxy returns a 504 because an upstream API worker took longer than the proxy timeout to respond.
Horizon 504 Gateway Timeout
The Horizon dashboard times out when backend API calls stall behind slow Keystone, Nova, or database responses.
Nova API timeout
Nova API requests hang or fail when compute services, the message bus, or the cell database become unresponsive.
Keystone authentication failure
Token issuance or validation fails, often from clock skew, stale Fernet keys, or a misconfigured identity backend.
Cinder scheduler timeout
The Cinder scheduler cannot place a volume in time because backends are slow, full, or not reporting capacity.
No valid backend was found
Cinder rejects a volume request because no storage backend passed the filters and capacity weighers.
Filtering removed all hosts
The Nova scheduler eliminated every candidate host, leaving no compute node able to satisfy the request.
Volume stuck creating
A Cinder volume never leaves the creating state, usually due to a driver, backend, or scheduler stall.
Neutron L3 agent dead
The neutron-l3-agent is reported dead, so routers stop forwarding traffic and floating IPs go unreachable.
Neutron DHCP agent down
Instances fail to lease addresses because the DHCP agent is down or its namespace is misconfigured.
RabbitMQ RPC timeout
oslo.messaging RPC calls time out when RabbitMQ is overloaded, partitioned, or dropping heartbeats.
oslo.messaging MessagingTimeout
A service waited for an RPC reply that never arrived, pointing at a stalled agent or a broken message bus.
MariaDB connection timeout
OpenStack services stall on the Galera cluster when connections exhaust, flow control kicks in, or a node desyncs.
HAProxy backend down
One or more HAProxy backends on the OpenStack control-plane VIP are marked DOWN, so requests to that service fail or return 503.
Kolla-Ansible certificate error
TLS handshakes fail after certificates expire or are rotated without a matching Kolla-Ansible reconfigure.
Placement API error
Scheduling breaks when the Placement service returns conflicts or stale resource provider allocations.
Nova compute service down
A hypervisor is marked down, so the scheduler skips it and instances on that host lose management.
VM stuck spawning
An instance never finishes building because image, network, or volume setup failed on the compute node.
VM stuck deleting
An instance hangs in the deleting task state when a volume detach, port cleanup, or RPC call never completes.
Image upload failure
Glance leaves an image stuck saving or errors on import when the store backend or conversion pipeline fails.
Glance image unavailable
An image cannot be downloaded or booted because the Glance store is unreachable or the data is corrupt.
Live migration failure
A live migration aborts due to CPU, storage, or network mismatches between the source and destination hosts.
Floating IP unreachable
A floating IP stops passing traffic when NAT rules, the L3 agent, or the router namespace are misconfigured.
Metadata service unavailable
Instances cannot fetch metadata or cloud-init data when the metadata agent or proxy path is broken.
OpenStack endpoint misconfiguration
Clients fail to reach a service when the Keystone catalog lists a wrong, internal, or unversioned endpoint URL.
Validate your config before you redeploy
Catch the structural mistakes that cause outages — 100% in your browser, nothing uploaded.
OpenStack Troubleshooting Hubs
Fix a whole class of OpenStack errors at once — each hub gathers the related guides for one failure class.
OpenStack Nova Compute & Scheduling Errors
Fix OpenStack Nova failures — No valid host was found, instance failed to spawn, no allocation candidates, live-migration and placement errors — with the exact nova and placement commands.
Open hubOpenStack Neutron Networking Errors
Fix OpenStack Neutron failures — port binding failed, VIF plugging timeout, no more IP addresses, floating IP pool not found, dead OVS/DHCP/L3 agents — with the exact neutron and ovs commands.
Open hubOpenStack Cinder Block Storage Errors
Fix OpenStack Cinder failures — no weighed backends, volume stuck creating or in error, image unacceptable, backup failures, LVM/Ceph backend errors — with the exact cinder commands.
Open hubBest OpenStack Prompts
Turn symptoms, logs, and config into a structured plan with prompts tuned for OpenStack.
Keystone token latency debug
Trace slow token validation behind API 504s and timeouts
Use this promptOctavia load balancer troubleshooting
Debug LB listeners, pools, and health monitors
Use this promptDownload the OpenStack Troubleshooting Runbook Pack
Control-plane runbooks for chasing 504s and RPC timeouts across HAProxy, Keystone, Nova, Cinder, Neutron, RabbitMQ, and MariaDB.
- 504 top-to-bottom triage checklist
- RabbitMQ RPC / oslo.messaging playbook
- Cinder scheduler timeout path
- Neutron L3 agent recovery
- Kolla-Ansible restart decision tree
All OpenStack Troubleshooting Guides
Grouped by failure-mode type — each guide covers cause, fix, validation, and prevention.