[error] ** (Ecto.NoPrimaryKeyValueError) struct while updating. insert working fine

Can you show the CustomerSchema.changeset function? Maybe also ShopRestApis.Context.CustomerContext.update?

defmodule ShopRestApis.Schema.CustomerSchema do
  use Ecto.Schema
  import Ecto.Changeset

  @fields [
    :id,
    :first_name,
    :last_name,
    :address,
    :landmark,
    :city,
    :state,
    :postcode,
    :mobile,
    :phone,
    :email,
    :company_name,
    :tax_code,
    :type,
    :status,
    :jobs,
    :shop_id
  ]
  @validation_fields [:first_name, :mobile, :type, :status]

  @primary_key {:id, :binary_id, autogenerate: false, read_after_writes: true}
  @foreign_key_type :binary_id
  schema "customer" do
    field :first_name, :string
    field :last_name, :string
    field :address, :string
    field :landmark, :string
    field :city, :string
    field :state, :string
    field :postcode, :string
    field :type, :string
    field :status, :string
    field :mobile, :string
    field :phone, :string
    field :email, :string
    field :company_name, :string
    field :tax_code, :string
    field :jobs, :integer

    belongs_to :shop, ShopRestApis.Schema.ShopSchema,
      foreign_key: :shop_id,
      type: @foreign_key_type

    timestamps(type: :utc_datetime)
  end

  @doc false
  def changeset(_, attrs) do
    %__MODULE__{}
    |> cast(attrs, @fields)
    |> validate_required(@validation_fields)
  end
end

update function

  def update(%CustomerSchema{} = data, attrs) do
    data
    |> CustomerSchema.changeset(attrs)
    |> Repo.update_all()
  end

Update isn’t going to work unless you use the first argument to changeset

i dont know what to say. stupid mistake. thank you very much.