Laravel migration (errno: 150 "Foreign key constraint is incorrectly formed")

Question

Since increments() creates an unsigned integer column, you need to define the foreign key column as unsigned integer too.

Default migrations in Laravel 6+ use bigIncrements(), so you need to use unsignedBigInteger() method:

$table->unsignedBigInteger('order_id');

https://laravel.com/docs/6.x/migrations#foreign-key-constraints

For default migrations in older versions of Laravel use unsignedInteger() method:

$table->unsignedInteger('order_id');

Or:

$table->integer('order_id')->unsigned();

https://laravel.com/docs/5.5/migrations#foreign-key-constraints

the foreign key must be an "unsignedBigInteger" and it will be fixed, something like this:

$table->unsignedBigInteger('user_id');

$table->foreign('user_id')->references('id')->on('users');

Primary key and foreign key should be in the same data type.

If the primary key is using unsigned big_integer, the foreign key should also be using unsigned big_integer.

In case laravel 5.8 uses bigIncrements by default when generating new migration (see this pull request), you should make sure that your foreign key is also unsigned big_integer or you will get error.

Table users:

Schema::create('users', function (Blueprint $table) {
    $table->bigIncrements('id');
    $table->string('name');

    ...

}

Table orders:

Schema::create('orders', function (Blueprint $table) {
    $table->bigIncrements('id');
    $table->unsignedBigInteger('user_id');

    ...

    $table->foreign('user_id')->references('id')->on('users');
}

Hope this helps.

I was also getting the same error. What i was doing in users table is,

$table->unsignedInteger('role_id')->default(2); table->foreign('role_id')->references('id')->on('roles')->onDelete('cascade');

But i have created the role table after creating users table. So, i edited the role migration file name date before the users table filename date. Like this,

2013_01_22_091213_create_roles_table.php
2014_10_12_000000_create_users_table.php

And finally it works. Maybe sometime you may get this problem. So, i posted it.

Laravel 5.8.3 comes with $table->bigIncrements('id');

change it to

$table->increments('id');
$table->integer('order_id')->unsigned();