Setting a foreign key bigInteger to bigIncrements in Laravel 5.4

Reason is primary and foreign references must be of same type.

bigIncrements() wants unsignedBigInteger()

and increments() wants unsignedInteger()

If you are using

$table->bigIncrements('id'); as a primary key in a users table:

then use

$table->unsignedBigInteger('user_id'); as foreign key

And if you are using $table->increments('id'); as a primary key in a users table then use

$table->unsignedInteger('user_id'); as freign key.



$table->increments(); creates just integer and $table->bigIncrements(); creates big integer. 

so the reference type must be the same.

Read more https://laravel.com/docs/4.2/schema#adding-columns

Remove unsigned() from:

$table->bigIncrements('id')->unsigned();

And the other migration should look like this:

$table->bigInteger('user_id')->unsigned();
$table->foreign('user_id')->references('id')->on('users')->onDelete('cascade');
....
$table->index('user_id');

The problem is that bigIncrements returns an unsignedBigInteger. In order to work the Foreign key must be an unsigned big integer with index().