Setting the value to custom field

Problem: Error occur when tries to set the value of custom field in after submit context.

Solution:In after submit context in order to set the value to custom field it is better to use record.submitFields()

  record.submitFields({
                                type: record.Type.ITEM_FULFILLMENT,

                                id: newRecord.id,
                                values: {
                                    'custbody_jj_fulfillment_id': newIFID
                                }
                            });