Step by Step Guide to solve n8n Database Authentication Errors
Who this is for: Developers and DevOps engineers who self‑host n8n (Docker, Docker‑Compose, or Kubernetes) and encounter “Database Authentication Error” at startup. We cover this in detail in the n8n Authentication Errors Guide.
Quick Diagnosis
| Quick Fix | How to Apply |
|---|---|
| 1. Verify DB user & password | Open the .env (or Docker‑Compose) file and confirm DB_USER and DB_PASSWORD match the credentials in your DB console. |
| 2. Check DB host/port | Ensure DB_HOST points to the correct hostname/IP and DB_PORT matches the DB service (PostgreSQL 5432, MySQL 3306, etc.). |
| 3. Test connectivity from the n8n container | docker exec -it <n8n_container> bash → nc -zvw3 $DB_HOST $DB_PORT – you should see succeeded. |
| 4. Restart n8n after changes | docker compose up -d --force-recreate n8n (or npm run start if self‑hosted). |
Apply the first step that fails; the error disappears after the corrected credentials are loaded.
1. Why n8n Throws a “Database Authentication Error”
If you encounter any self signed certificate error resolve them before continuing with the setup.
n8n connects to a relational database (PostgreSQL, MySQL/MariaDB, or SQLite) during startup. The connection code can be visualised in two short snippets.
Load environment variables
const cfg = {
type: process.env.DB_TYPE,
host: process.env.DB_HOST,
port: Number(process.env.DB_PORT),
};
Create the DB connection
await createConnection({
...cfg,
username: process.env.DB_USER,
password: process.env.DB_PASSWORD,
database: process.env.DB_DATABASE,
});
If any of the variables are missing, malformed, or don’t match the DB server, the driver throws:
error: password authentication failed for user "..."
The generic message may mask several underlying problems:
| Root cause | Typical symptom |
|---|---|
| Wrong password | Authentication fails even though the user exists. |
| Non‑existent user | Driver reports “password authentication failed”. |
Host‑based denial (PostgreSQL pg_hba.conf) |
Connection rejected before password check. |
SSL/TLS mismatch (DB_SSL flag) |
Server requires TLS but client connects plain‑text. |
Identifying which sub‑issue applies lets you apply a surgical fix.
2. Step‑by‑Step Diagnosis Checklist
If you encounter any proxy authentication required resolve them before continuing with the setup.
| Step | Action | Expected Result | EEFA Note |
|---|---|---|---|
| 1 | Open the environment source (.env, docker‑compose.yml, Kubernetes ConfigMap). |
All DB_* variables are present. |
In production, keep .env out of source control; use a secrets manager. |
| 2 | Confirm the DB user exists on the DB server. | SELECT 1 FROM pg_roles WHERE rolname='${DB_USER}'; (Postgres) returns a row. |
Avoid using superuser accounts; create a dedicated n8n role with least‑privilege. |
| 3 | Verify the password works directly on the DB host. | psql -U $DB_USER -h $DB_HOST -W (or mysql -u $DB_USER -p) logs in successfully. |
Do not store passwords in plain text; use Docker secrets or Vault. |
| 4 | Test network reachability from the n8n runtime. | nc -zvw3 $DB_HOST $DB_PORT → *succeeded*. |
Firewalls/NAT must allow traffic on the DB port; block external access in production. |
| 5 | Check SSL/TLS settings (DB_SSL). |
If DB requires SSL, set DB_SSL=true and provide DB_SSL_CA. |
Using self‑signed certs without DB_SSL_REJECT_UNAUTHORIZED=false will break connections. |
| 6 | Restart the n8n process after any change. | No “Database Authentication Error” in logs. | Restart ensures the new env vars are loaded; in Kubernetes use a rolling restart. |
3. Common Mis‑configurations & How to Fix Them
3.1 Typo in Variable Names
| Wrong | Correct |
|---|---|
| DB_USR | DB_USER |
| DB_PWD | DB_PASSWORD |
| DB_HOSTNAME | DB_HOST |
Fix – Edit the .env (or ConfigMap) and rename the keys, then restart n8n.
3.2 Accidentally Using SQLite in Production
If DB_TYPE=sqlite but a PostgreSQL server is running, n8n will look for a local file and emit an authentication‑style error.
Fix – Set DB_TYPE=postgres (or mysql) and supply the proper connection details.
3.3 Host‑Based Authentication (PostgreSQL)
PostgreSQL’s pg_hba.conf may reject connections from the n8n container IP.
# Allow any container on the same Docker network host all all 172.18.0.0/16 md5
Fix – Add an appropriate host line, reload PostgreSQL (SELECT pg_reload_conf();), and verify the Docker network subnet matches.
3.4 SSL Mismatch
When the DB requires TLS but DB_SSL is omitted, the driver falls back to plain text and the server rejects the login.
Fix – Add the SSL flags to the environment:
DB_SSL=true DB_SSL_CA=/run/secrets/db-ca.pem # optional, required for self‑signed CA
Mount the CA file into the container (Docker secret or volume) and restart n8n.
4. Real‑World Example: Docker‑Compose Fix
Below is a production‑ready docker-compose.yml split into focused snippets.
4.1 PostgreSQL Service (4 lines)
postgres:
image: postgres:16-alpine
environment:
POSTGRES_USER: n8n_user
POSTGRES_PASSWORD: ${POSTGRES_PASSWORD}
4.2 n8n Service (5 lines)
n8n:
image: n8nio/n8n:latest
depends_on:
- postgres
environment:
DB_TYPE: postgres
DB_HOST: postgres
DB_USER: n8n_user
DB_PASSWORD: ${POSTGRES_PASSWORD}
4.3 Ports, Volumes & Networks (4 lines)
ports:
- "5678:5678"
volumes:
- n8n_data:/home/node/.n8n
networks:
default:
driver: bridge
Key points
DB_PASSWORDis injected from an external variable (or Docker secret) – never hard‑code it.depends_onguarantees PostgreSQL starts first, but you still need to wait for DB readiness (e.g.,command: ["sh","-c","until pg_isready -h postgres; do sleep 1; done && n8n"]).
5. Verifying the Fix – Log Samples
5.1 Before fix (error)
2024-09-12 03:14:02.123 [error] Error: password authentication failed for user "n8n_user"
at Connection.<anonymous> (.../node_modules/pg/lib/connection.js:123:15)
5.2 After fix (success)
2024-09-12 03:15:10.456 [info] Database connection established (PostgreSQL, db=n8n, user=n8n_user) 2024-09-12 03:15:10.457 [info] n8n ready on http://0.0.0.0:5678
If the error persists after confirming credentials, revisit the Step‑by‑Step Diagnosis Checklist and focus on network reachability and SSL settings.
6. Production‑Grade EEFA (Expertise, Authority, Trust, Experience) Tips
| Area | Best Practice | Why It Matters |
|---|---|---|
| Secrets Management | Use Docker secrets, Kubernetes Secret, or HashiCorp Vault for DB_PASSWORD. |
Prevents credential leakage in logs or source control. |
| Least‑Privilege DB Role | Grant CONNECT, SELECT, INSERT, UPDATE, DELETE on the n8n schema only. |
Limits blast radius if the n8n container is compromised. |
| TLS Encryption | Enforce DB_SSL=true and verify server certificate. |
Protects credentials in transit; required for compliance (PCI, GDPR). |
| Health‑Check & Auto‑Recovery | Add a healthcheck that runs pg_isready (or mysqladmin ping). |
Orchestrator restarts n8n only when DB is reachable. |
| Backup Strategy | Schedule daily logical dumps (pg_dump) and store off‑site. |
Guarantees workflow continuity after accidental DB loss. |
| Monitoring | Export DB connection metrics to Prometheus (e.g., pg_exporter). |
Early detection of connection spikes or authentication failures. |
8. Next Steps
- Secure your n8n instance – enable HTTPS with a reverse proxy (NGINX/Traefik).
- Scale n8n horizontally – configure a shared external DB and Redis for queueing.
- Migrate from SQLite to PostgreSQL – step‑by‑step migration guide.
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