Format Form Validation Message in Laravel 5

You can set custom validation messages in the resources/lang/en/validation.php file:

'custom' => [
    'date' => [
        'date' => 'The <strong>:attribute</strong> is not a valid date.',
    ],
],

If you want the attribute to be bold on all date validation messages (regardless of the field name), then you can set the message for the date key:

'date' => 'The <strong>:attribute</strong> is not a valid date.',

use str_replace and then ask blade to parse the output as an html text, like this:

{!! str_replace( 'Date' , '<b>Date</b>' , 'The Date is not a valid date')  !!}

If you're using the basic validation error display and want to show the name of the field in bold, you can:

Using the 'en' language as an example.

• Add the name of the field in a language file (resources/lang/en/validation.php) inside the attributes key:

  <?php
  return [
      'attributes' => [
          'my_field' => '<b>My Field</b>'
      ]
  ];
  

• In the validation message display, just change the {{ $error }} to {!! $error !!}