Keep getting Unknown or bad timezone from Carbon Laravel

I'm trying to add 2 months to a date with Carbon, but I keep getting this error:

InvalidArgumentException in Carbon.php line 252:
Unknown or bad timezone (2017-02-25 14:25:24)

Here is my code:

<?php
public function giveMonths(Request $request)

    {   

        $query = DB::table('users')->where('level', '=', 2)->get();

        foreach ($query as $row) {

            $id = $row->id;

            $expires = $row->expires;

            $newDate = Carbon::now($expires)->addMonths(2);

            dd($newDate);
        }

In "app.php" the timezone is set this way:

'timezone' => 'America/Sao_Paulo'

The timezone stored in the DB is in this format:

2017-02-25 03:51:12

How can I solve this problem?

via Chebli Mohamed