Octopus "The Tentacle is offline / unavailable" in CI
Octopus tried to communicate with the Tentacle agent on a target and could not. A listening Tentacle is not reachable on its port, or a polling Tentacle has not called home, so the machine is treated as offline and the deployment to it fails.
What this error means
The deploy fails with "The Tentacle web-01 is offline or could not be contacted" or a connection timeout to the Tentacle during a health check or deployment.
Deploying to web-01...
The Tentacle 'web-01' is offline or unavailable and could not be contacted.Common causes
The Tentacle service is stopped or unreachable
A listening Tentacle is down or blocked on its port, or a polling Tentacle stopped connecting to the server, so it cannot be contacted.
A network or thumbprint mismatch
A firewall change, DNS change, or a certificate thumbprint mismatch between server and Tentacle prevents the trusted connection.
How to fix it
Restore and verify the Tentacle connection
- Confirm the Tentacle service is running on the target.
- Check the port and firewall for listening Tentacles, or connectivity to the server for polling ones.
- Run a health check so the target returns to Healthy before deploying.
octo health-check --environment "Production" \
--server "$OCTOPUS_URL" --apiKey "$OCTOPUS_API_KEY"Fix a thumbprint or trust mismatch
If the connection fails on trust, re-register the Tentacle so the server and target thumbprints match.
How to prevent it
- Monitor Tentacle health and alert on offline targets.
- Keep firewall and DNS rules stable for listening Tentacles.
- Run a health check before deploys so offline targets surface early.