How to Fix Kong Database Migration Error

In this tutorial, you'll learn about How to Fix Kong Database Migration Error. We cover key concepts, practical examples, and best practices.

Kong database migration fails with Error: [<a href="/databases/postgresql/">PostgreSQL</a> error] could not run bootstrap migration or migrations already up to date when running kong migrations bootstrap — the database schema is inconsistent with the Kong version.

The Problem

$ kong migrations bootstrap
Error: /usr/local/share/lua/5.1/kong/cmd/migrations.lua:48:
[PostgreSQL error] relation "schema_migrations" does not exist

Step-by-Step Fix

Step 1: Check the current Kong version

kong version

Step 2: Reset and bootstrap migrations

# Warning: This removes all existing data
kong migrations reset
kong migrations bootstrap

Step 3: Handle migration conflicts

# If "migrations already up to date" error
kong migrations up
# Or re-run bootstrap with force
KONG_DATABASE=postgres kong migrations bootstrap -f

Step 4: Verify migration status

kong migrations status

Expected:

Database is up-to-date

Step 5: Check PostgreSQL connection

psql -h localhost -U kong -d kong -c "SELECT * FROM schema_migrations;"

Prevention Tips

• Always back up the Kong database before major version upgrades
• Run kong migrations status before any upgrade
• Use database-less (DB-less) mode for simple deployments
• Keep Kong and PostgreSQL versions compatible

Common Mistakes with db migration

1. Using head and tail instead of pattern matching, causing runtime errors on empty lists
2. Forgetting that lazy evaluation defers computation until the value is forced, causing space leaks with unevaluated thunks
3. Using return to exit a function early instead of wrapping a pure value in the monad

These mistakes appear frequently in real-world KONG code. DodaTech's contributors have identified these patterns through analysis of open-source projects and production systems.

Practice Exercise

Write a pure function that safely divides two integers using Maybe, then test it with edge cases like division by zero and negative numbers.

This exercise reinforces the concepts covered in this guide. Try implementing it before checking online solutions.

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