Troubleshooting Prisma DB Seeding Failure

This note documents the process of resolving a PrismaClientKnownRequestError that occurred during database seeding. The root cause was a mismatch between the Prisma schema and the actual database state.

1. The Initial Problem: Seeding Fails

When running pnpm prisma db seed, the process failed with an error indicating a missing column in the database.

pnpm prisma db seed

Error Output:

Error during seeding: PrismaClientKnownRequestError: 
Invalid `prisma.cart.create()` invocation in
/path/to/project/packages/database/prisma/seed.ts:804:35

→ 804 const cart1 = await prisma.cart.create(
The column `promo_discount_amount` does not exist in the current database.
  code: 'P2022',
  meta: { modelName: 'Cart', column: 'promo_discount_amount' },
  clientVersion: '6.16.2'
}

This error (P2022) clearly shows that the seed.ts script was trying to insert data into the promo_discount_amount column of the Cart table, but this column did not exist in the database.

2. Failed Attempts to Fix

Several attempts were made to fix the issue using standard Prisma migration commands, but they failed due to the database being in a broken or inconsistent state.

Attempt A: prisma migrate dev

The first instinct was to create a new migration to add the missing column.

pnpm prisma migrate dev --name add_promo_discount_amount_to_cart

This failed because a previous, unsuccessful migration had left the database in a state that prevented new migrations from being applied.

Attempt B: prisma migrate reset

The next step was to reset the database, hoping to clear the bad state and re-apply all migrations from scratch.

pnpm prisma migrate reset

While the reset completed, the subsequent automatic seeding failed with the exact same error. This happened because migrate reset only applies existing migration files. Since a migration for promo_discount_amount was never successfully created, the column was still missing after the reset.

Attempt C: Resolving and Deleting Failed Migrations

Further attempts to resolve the failed migration state and manually delete the broken migration files also led to a dead end, with Prisma detecting a discrepancy and requiring another reset.

Written by A.M. Rinas