Flyway "Unable to obtain connection from database" in CI
By Daniel Zoghalchali·Latchkey
Flyway could not open a JDBC connection to the database. The driver never reached a usable server - a connectivity, readiness, or URL problem, not a migration-content problem.
What this error means
flyway migrate/info fails up front with "Unable to obtain connection from database", wrapping a JDBC "Connection refused" or timeout. It frequently passes on retry once a database service finishes starting.
flyway output
ERROR: Unable to obtain connection from database
(jdbc:postgresql://db:5432/app) for user 'app':
Connection to db:5432 refused.
Common causes
Database service not ready
A database service container is still starting when Flyway runs, so the JDBC connection is refused. This is transient and clears once the service is up.
Wrong JDBC URL or credentials
An incorrect host/port in the JDBC URL, or wrong user/password, prevents the connection from being established at all.
Transient network blip
A brief connectivity drop to a remote database can cause an intermittent connection failure that succeeds when retried.
How to fix it
Wait for the database, then migrate
Block on readiness so Flyway does not race the database boot.
Terminal
until pg_isready -h db -p 5432; do sleep 1; done
flyway -url=jdbc:postgresql://db:5432/app migrate
Verify the JDBC URL and credentials
Confirm host, port, and database name in the JDBC URL match the reachable service.
Check the user/password against the database service env.
Use connectRetries so Flyway waits for a briefly-unavailable database.
Use connectRetries so Flyway tolerates a slow-starting database.
Gate Flyway on a readiness check or service healthcheck.
Keep the JDBC URL and credentials in sync with the CI network.
Frequently asked questions
What causes ""Unable to obtain connection""?
A database service container is still starting when Flyway runs, so the JDBC connection is refused. This is transient and clears once the service is up.
How do I fix "Unable to obtain connection"?
Block on readiness so Flyway does not race the database boot.
Can Latchkey fix this automatically?
Yes. Latchkey runs your GitHub Actions on managed runners that detect this failure, apply the fix, and retry the job automatically - self-healing is on by default.
