Unsupported Operand Types theme_image_style I'm using the following code to generate a thumbnail and it's URI. The URI works on its own (though it 404's) but whenever I add theme_image_style function it gives a fatal error: "Unsupported operand types in /theme.inc on line 1088"

$image_fields_src = array_column($image_fields, 'uri' );

// thumbnail uri
$thumburi = image_style_path('thumbnail', $image_fields_src[0]);
// generate thumbnail
$thumbnail = theme_image_style('thumbnail', $thumburi );
According to theme_image_style page you tried wrong parameters, 

as an example, your code should be something like the following snippet

$variables = array(
        'style_name' =&gt; 'thumbnail',
        'path' =&gt; $image_fields[LANGUAGE_NONE][0]['uri'],
        'width' =&gt; $image_fields[LANGUAGE_NONE][0]['width'],
        'height' =&gt; $image_fields[LANGUAGE_NONE][0]['height']
);
$thumbnail_image = theme_image_style($variables);


and in short

$thumbnail_image = theme('image_style', array(
        'style_name' =&gt; 'thumbnail',
        'path' =&gt; $image_fields[LANGUAGE_NONE][0]['uri'],
));