Each model must have at least one unique criteria that has only required fields.

Not specified by the original author.

TL;DR: Add @id, @unique, or a composite @@id/@@unique to your model, on fields that are required (not optional). Then npx prisma validate passes. Prisma needs at least one unique way to address a single record.

error: Each model must have at least one unique criteria that has only required fields.

Steps

1. Find the model the error names and give it a unique criterion. Pick the first option that fits:

   model User {
     id    Int    @id @default(autoincrement())
     email String @unique
   }

   or for composite keys:

   model Membership {
     userId String
     orgId  String
     @@id([userId, orgId])
   }

   Expected: the criterion covers only required fields (no ? on any of them).

2. Run validation:

   npx prisma validate

   Expected: The schema at prisma/schema.prisma is valid.

3. Regenerate the client and continue your migration:

   npx prisma generate

   Expected: Generated Prisma Client with no validation errors.

When to use

• prisma validate, prisma generate, or prisma migrate dev fails with the exact unique-criteria message
• You are modeling a join table or a legacy table with no primary key

When not to use

• The error is about a datasource URL or protocol: that is a different P1012 message
• You actually want keyless models (MongoDB): use @@ignore or the MongoDB connector rules instead

Compatibility

Prisma schema validation, all versions 2.x through 7.x. PostgreSQL, MySQL, SQL Server, SQLite.

Variant phrasing: Each model must have at least one unique criteria that has only required fields on a model where every field is optional

Making the unique field required is the point: @unique on an optional field still fails validation. Change the field to required or pick a different field.

Why it happens

Prisma Client's findUnique, update, and delete need a guaranteed-unique lookup. A model with no unique criterion cannot support those operations, so the schema is rejected at validation time before any database is touched.

Edge cases

• Legacy tables truly without a unique column: add a surrogate auto-increment id in the migration.
• Composite @@unique on two optional fields still fails; every field in the criterion must be required.
• Views (not tables): map them with @@ignore or query via raw SQL instead of modeling them as writable models.

A long-standing Prisma issue asked why models without any unique field are rejected at validation time. The confirmed resolution from the Prisma team: every model needs at least one unique criterion over required fields, so queries like findUnique have something to target. The fix is to add @id to a primary key field, @unique to a naturally unique field, or @@id([a, b]) / @@unique([a, b]) for composite keys, all on required (non-optional) fields. After adding the attribute, validate and generate pass. Source: https://github.com/prisma/prisma/issues/7944