The field in where clause of the upsert query should be unique.

In this case, the email field is not unique due to which you are getting this error.

Updating schema file by adding @unique attribute to the email field will solve the issue.

model prismaUser {
  id           Int    @id @default(autoincrement())
  name         String @db.VarChar(255)
  email        String @unique @db.VarChar(255)
  profileViews Int
  role         String @db.VarChar(255)
}

I fixed it by removing the User from the update object. I suppose if a record already exists, it is already "connected", so trying to reconnect it again throws an error.

Working code:

  const data = {
    expiresAt: new Date(Date.now() + ms("10m")),
    token: randomize("0", 6),
  }
  await db.passwordResetAuthorization.upsert({
    where: {
      userId: user.id,
    },
    create: {
      User: {
        connect: {
          id: user.id,
        },
      },
      ...data,
    },
    update: data,
  })

Sorry for this, I have changed and found another way to do this. If anyone was curious on how i changed it (for future use if anyone gets stuck and gets the same results like this)

    const prisma = new PrismaClient()
    const { username, email, hashPassword } = await request.json();
    let verified = crypto.randomBytes(32).toString('hex');

    const userExist = await prisma.users.findFirst({ where: { OR: [{ username }, { email }] } })
    if (userExist === null) {
        await prisma.users.create({ data: { username, email, hashPassword, verified } })
        return new NextResponse('Success!', { status: 201 })
    } else {
        return new NextResponse("Sorry, username and or email already exists!", { status: 500 })
    }