Have you uploaded large images to your site?

I have, but then have deleted the images and still the error persists.

This is the other info it gives me for the error:

if (false === imagealphablending($resource, false) || false === imagesavealpha($resource, true)) {
throw new RuntimeException('Image ' . $operation . ' failed');
}

if (function_exists('imageantialias')) {
imageantialias($resource, true);
}

$transparent = imagecolorallocatealpha($resource, 255, 255, 255, 127);
imagefill($resource, 0, 0, $transparent);
imagecolortransparent($resource, $transparent);

return $resource;
}

You could try allocating 512MB of memory - sometimes 256 isn't enough.

Hello,

Thank you for the reply. What is the best way to change this?

Cheers

Have a dredge around CPanel php settings (if relevant).