If you look at the entire block that gives that error, you'll see that this error stems from the update being out of bounds of the original map so they're rejected

// Reject updates which have any out-of-bounds data.
if (update->x < 0 || update->y < 0 || current_map_.info.width < update->x + update->width ||
    current_map_.info.height < update->y + update->height)
{
    setStatus(StatusProperty::Error, "Update", "Update area outside of original map area.");
    return;
}

So, it appears that your update is out of bounds.