Prisma migrate dev shadow database error
Problem
When using Prisma with cloud-hosted databases (Prisma Postgres, Neon, Supabase, etc.),
prisma migrate dev fails with shadow database errors like:Error: P3006 Migration 20251005080724_init failed to apply cleanly to the shadow database. Error: type "ParentageRole" already exists
This happens because Prisma tries to use the same database for both:
1. The application's main database
2. The shadow database (used for migration validation)
Current Documentation Gap
The official migration docs mention shadow databases, but:
-
No clear guidance for cloud database providers-
No step-by-step setup for Prisma Postgres specifically-
Error messages don't point users to the solution-
Many users resort to migrate reset thinking migrations are brokenSolution (that should be documented)
Create a separate shadow db.For Vercel Integration of Prisma Postgres,
1. Go to Projects->Storage->Create Database-> Select Prisma Postgres-> Select region->Create->Add "SHADOW" as environment variable prefix.
2. Do a
vercel env pull 3. Set
shadowDatabaseUrl in schema.prisma to SHADOW_DATABASE_URL
