This happened when registering

[Distortion]

Did you add kyttias's welcome pm code? If so, add your username to where it says YourUsernameHere in the code. The same goes with message title and content. Ex. below:

PHP Code:

if($mysidia->input->post("submit")){
    $document->setTitle($this->lang->success_title);
    $document->addLangvar($this->lang->success.$mysidia->input->post("username").$this->lang->success2);

    $pm = new PrivateMessage(); // Send them a welcoming message
    $pm->setsender('SapphirePhoenix');
    $pm->setrecipient(htmlentities(addslashes(trim($mysidia->input->post("username")))));
    $pm->setmessage("Welcome", "Test text.");
    $pm->post();  
    
    return;
} 


The first error has nothing to do with it. It's the same problem I have as well.