Erro ao criar uma chave estrangiera via Migration

Ao tentar inserir uma foreign key por uma migration, eu SEMPRE tenho o mesmo erro SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails (diariodebordo.#sql-3618_a3, CONSTRAINT users_id_cargo_foreign FOREIGN KEY (id_cargo) REFERENCES cargos (id)) (SQL: alter table users add constraint users_id_cargo_foreign foreign key (id_cargo) references cargos (id))

Já passei horas e mais horas procurando na internet e não consigo achar uma solução

<?php

use Illuminate\Database\Migrations\Migration;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Support\Facades\Schema;

class AddTabelaCargos extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('cargos', function (Blueprint $table){
            $table->increments('id');
            $table->string('nome_cargo');
            $table->text('permissoes');
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        //
    }
}

<?php

use Illuminate\Database\Migrations\Migration;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Support\Facades\Schema;

class AddIdCargoNaTabelaUsers extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::table('users', function (Blueprint $table){
            $table->unsignedInteger('id_cargo');
            $table->foreign('id_cargo')->references('id')->on('cargos');
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        //
    }
}