Next-auth getSession returns null when deployed to vercel but works fine whe I run it locally

When I run this code locally it works fine but when I deployed it to vercel am getting session.user.email is undefined. I am using GraphQL, Nexus and Prisma

t.field('createProject', {
      type: 'Project',
      args: {
        name: nonNull(stringArg()),
        description: nonNull(stringArg()),
        website: stringArg(),
        sourceCode: stringArg(),
        // userId: stringArg(),
      },
      async resolve(_, args, ctx) {
        // console.log(user)
        try {
          const req = ctx.req
          const session = await getSession({ req })
          // // console.log(session)
          // const user = await ctx.prisma.user.findUnique({
          //   where: { email: session?.user.email },
          // })
          return ctx.prisma.project.create({
            data: {
              name: args.name,
              description: args.description,
              website: args.website,
              user: { connect: { email: session?.user?.email } },
              sourceCode: args.sourceCode,
            },
          })
        } catch (error) {
          console.log(error)
        }
      },
    })