# Troubleshooting (Prisma ORM v6) (/docs/orm/v6/prisma-migrate/workflows/troubleshooting) Troubleshooting issues with Prisma Migrate in a development environment. Location: ORM > v6 > Prisma Migrate > Workflows > Troubleshooting This guide describes how to resolve issues with Prisma Migrate in a development environment, which often involves resetting your database. For production-focused troubleshooting, see: - [Production troubleshooting](/guides/prisma-migrate-v6-workflows-patching-and-hotfixing) - [Patching / hotfixing production databases](/guides/prisma-migrate-v6-workflows-patching-and-hotfixing) > \[!WARNING] > This guide **does not apply for MongoDB**. > Instead of `migrate dev`, [`db push`](/guides/prisma-migrate-v6-workflows-prototyping-your-schema) is used for [MongoDB](/guides/core-concepts-v6-overview-databases-mongodb). ## Handling migration history conflicts A migration history conflict occurs when there are discrepancies between the \*_migrations folder in the file system_\* and the **`_prisma_migrations` table in the database**. #### Causes of migration history conflict in a development environment - A migration that has already been applied is later modified - A migration that has already been applied is missing from the file system In a development environment, switching between feature branches can result in a history conflict because the `_prisma_migrations` table contains migrations from `branch-1`, and switching to `branch-2` might cause some of those migrations to disappear. > **Note**: You should [never purposefully delete or edit a migration](/guides/prisma-migrate-v6-understanding-prisma-migrate-migration-histories#do-not-edit-or-delete-migrations-that-have-been-applied), as this might result in discrepancies between development and production. #### Fixing a migration history conflict in a development environment If Prisma Migrate detects a migration history conflict when you run `prisma migrate dev`, the CLI will ask to reset the database and reapply the migration history. ## Schema drift Database schema drift occurs when your database schema is out of sync with your migration history - the database schema has 'drifted away' from the source of truth. #### Causes of schema drift in a development environment Schema drift can occur if: - The database schema was changed _without_ using migrations - for example, by using [`prisma db push`](/guides/reference-6-v6-reference-prisma-cli-reference#db-push) or manually changing the database schema. > **Note**: The [shadow database](/guides/prisma-migrate-v6-understanding-prisma-migrate-shadow-database) is required to detect schema drift, and can therefore only be done in a development environment. #### Fixing schema drift in a development environment If you made manual changes to the database that you do not want to keep, or can replicate in the Prisma schema: 1. Reset your database: #### bun ```bash bunx prisma migrate reset ``` #### pnpm ```bash pnpm prisma migrate reset ``` #### yarn ```bash yarn prisma migrate reset ``` #### npm ```bash npx prisma migrate reset ``` 2. Replicate the changes in the Prisma schema and generate a new migration: #### bun ```bash bunx prisma migrate dev ``` #### pnpm ```bash pnpm prisma migrate dev ``` #### yarn ```bash yarn prisma migrate dev ``` #### npm ```bash npx prisma migrate dev ``` If you made manual changes to the database that you want to keep, you can: 1. Introspect the database: #### bun ```bash bunx prisma db pull ``` #### pnpm ```bash pnpm prisma db pull ``` #### yarn ```bash yarn prisma db pull ``` #### npm ```bash npx prisma db pull ``` Prisma will update your schema with the changes made directly in the database. 2. Generate a new migration to include the introspected changes in your migration history: #### bun ```bash bunx prisma migrate dev --name introspected_change ``` #### pnpm ```bash pnpm prisma migrate dev --name introspected_change ``` #### yarn ```bash yarn prisma migrate dev --name introspected_change ``` #### npm ```bash npx prisma migrate dev --name introspected_change ``` Prisma Migrate will prompt you to reset, then applies all existing migrations and a new migration based on the introspected changes. Your database and migration history are now in sync, including your manual changes. ## Failed migrations #### Causes of failed migrations in a development environment A migration might fail if: - You [modify a migration before running it](/guides/prisma-migrate-v6-workflows-customizing-migrations) and introduce a syntax error - You add a mandatory (`NOT NULL`) column to a table that already has data - The migration process stopped unexpectedly - The database shut down in the middle of the migration process Each migration in the `_prisma_migrations` table has a `logs` column that stores the error. #### Fixing failed migrations in a development environment The most direct way to handle a failed migration in a development environment is to address the root cause and reset the database. For example: - If you introduced a SQL syntax error by manually editing the database, update the `migration.sql` file that failed and reset the database: ```bash prisma migrate reset ``` - If you introduced a change in the Prisma schema that cannot be applied to a database with data (for example, a mandatory column in a table with data): 1. Delete the `migration.sql` file. 2. Modify the schema - for example, add a default value to the mandatory field. 3. Migrate: ```bash prisma migrate dev ``` Prisma Migrate will prompt you to reset the database and re-apply all migrations. - If something interrupted the migration process, reset the database: ```bash prisma migrate reset ``` ## Prisma Migrate and PgBouncer You might see the following error if you attempt to run Prisma Migrate commands in an environment that uses PgBouncer for connection pooling: ```bash Error: undefined: Database error Error querying the database: db error: ERROR: prepared statement "s0" already exists ``` See [Prisma Migrate and PgBouncer workaround](/guides/prisma-client-v6-setup-and-configuration-databases-connections-pgbouncer) for further information and a workaround. ## Related pages - [`Baselining a database`](/guides/prisma-migrate-v6-workflows-baselining): How to initialize a migration history for an existing database that contains important data. - [`Customizing migrations`](/guides/prisma-migrate-v6-workflows-customizing-migrations): How to edit a migration file before applying it to avoid data loss in production. - [`Data migrations`](/guides/prisma-migrate-v6-workflows-data-migration): How to migrate data using Prisma ORM with the expand and contract pattern. - [`Development and production`](/guides/prisma-migrate-v6-workflows-development-and-production): Development and production - [`Generating down migrations`](/guides/prisma-migrate-v6-workflows-generating-down-migrations): How to generate down migrations ## Related pages - [Authentication & Tools](./authentication-tools-index.md) - [Build](./build-index.md) - [Changelog](../changelog.md) - [Concepts](./concepts-index.md) - [Console commands](./console-commands-index.md) - [Contract Authoring](./contract-authoring-index.md) - [Core Concepts](./core-concepts-index.md) - [Data Modeling](./data-modeling-index.md) - [Database](./database-index.md) - [DB commands](./db-commands-index.md) # Agent Instructions Cite this page’s canonical URL and keep its documentation version. 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