name: n8n-supabase-workflow-debug

description: Debug n8n workflows connecting to Supabase REST API — common bugs, SQL updates, and workflow_history management on self-hosted Docker n8n

n8n + Supabase REST API Integration Debugging

Context

Debugging n8n workflows that connect to Supabase via REST API on self-hosted n8n (VPS Docker).

Common Issues and Solutions

1. n8n Supabase Node Bugs

The native n8n-nodes-base.supabase node has bugs with filters (select conditions) and fieldsUi parameters — errors like:

• - "At least one select condition must be defined" — even when match column IS set
• - "propertyValues[itemName] is not iterable" — internal node error
• - "Cannot read properties of undefined (reading 'node')" — internal n8n error

Solution: Use n8n-nodes-base.httpRequest instead of the native Supabase node. Works perfectly.

2. Supabase REST API via HTTP Request Node

`

URL: https://{project}.supabase.co/rest/v1/{table}?on_conflict={conflict_column}

Method: POST

Headers:

- apikey: {anon_key}

- Authorization: Bearer {anon_key}

- Prefer: resolution=merge-duplicates (for upsert)

- Content-Type: application/json

Body (specifyBody=json, jsonBody):

= {{ $json.data }} (from Code node transform)

`

3. workflow_history Table

n8n stores published workflow versions in workflow_history. Column names are case-sensitive and require double quotes:

• - "versionId" — NOT versionId
• - "workflowId" — NOT workflowId
• - "createdAt" — NOT createdAt

4. SQL UPDATE with JSON Content

When updating workflow_history.nodes directly via SQL, use dollar-quoting to avoid escaping issues:

`sql

UPDATE workflow_history

SET nodes = $json${"nodes": [...]}$json$

WHERE "versionId" = 'uuid-here';

`

NOT E'...' syntax — dollar-quoting is cleaner.

5. Updating Workflow via REST API

• - PATCH /rest/workflows/{id} — partial update (nodes only, no version bump)
• - PUT — full replace, creates new versionId
• - After PATCH: manually update workflow_history with the same nodes, using current activeVersionId

6. n8n Database Access (Docker)

`bash

docker exec -i n8n-postgres psql -U n8n -d n8n -c "SELECT ..."

`

Python on VPS for complex SQL updates:

`python

import subprocess

script = """

import json, subprocess

with open('/tmp/workflow_nodes.json') as f:

nodes = json.load(f)

nodes_json = json.dumps(nodes)

active_vid = 'uuid-from-workflow-entity'

sql = 'UPDATE workflow_history SET nodes = $json$' + nodes_json + '$json$ WHERE "versionId" = \\'' + active_vid + '\\';'

subprocess.run(['docker', 'exec', '-i', 'n8n-postgres', 'psql', '-U', 'n8n', '-d', 'n8n', '-c', sql], capture_output=True, text=True)

"""

Upload script to VPS via SCP, then run via SSH

`

7. Finding Real Column Names in Supabase

`bash

curl "https://{project}.supabase.co/rest/v1/{table}?limit=1" \

-H "apikey: {anon_key}" \

-H "Authorization: Bearer {anon_key}"

`

Check the returned JSON keys — column names in Supabase REST are case-sensitive.

8. Workflow Entity Key Columns

`sql

SELECT id, name, active, "activeVersionId", "versionId"

FROM workflow_entity

WHERE name LIKE '%keyword%';

`

Workflow History Structure

• - workflow_entity.activeVersionId = points to workflow_history.versionId of the ACTIVE published version
• - workflow_entity.versionId = the latest saved (draft) version
• - Publishing via UI creates a new workflow_history entry and updates activeVersionId
• - PATCH via API only updates workflow_entity.nodes, NOT workflow_history — need to update both manually

Debugging Commands

`bash

Check workflow executions

docker exec n8n-postgres psql -U n8n -d n8n -c \

'SELECT id, "workflowId", status, finished, mode, "startedAt", "stoppedAt" FROM execution_entity WHERE "workflowId" = '\''{id}'\'' ORDER BY "startedAt" DESC LIMIT 5;'

Check execution data (error details)

docker exec n8n-postgres psql -U n8n -d n8n -c \

'SELECT data FROM execution_data WHERE "executionId" = {exec_id};'

`

n8n REST API Authentication

Login via API to get session cookie:

`bash

curl -s -c cookies.txt https://n8n.example.com/rest/login \

-X POST -H "Content-Type: application/json" \

-d '{"emailOrLdapLoginId": "user@email.com", "password": "pass"}'

`

Then use -b cookies.txt for subsequent authenticated requests.

Supabase Anon Key Format

sb_ prefix = Share Bucket (wrong), sbp_ prefix = Project API key (also not the anon key).

The anon key is a JWT: eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9... — decode the second part to find project ref.