In HTMLForm there are already hidden field declared, so remove the unnecessary hidden field from HTMLForm Object
'get' Method
- Declaration in HTMLForm:-
$html .= Html::hidden( 'title', $this->getTitle()->getPrefixedText() ) . "\n";
- Problem
Actual url:- /index.php?limit=20&title=Special%3AListSignupDisplay
Expected url:- /index.php/Special:ListSignupDisplay?limit=20
In 'post' Method
Declaration in HTMLForm:-
$html .= Html::hidden( 'wpEditToken', $this->getUser()->getEditToken( $this->mTokenSalt ), [ 'id' => 'wpEditToken' ] ) . "\n"; $html .= Html::hidden( 'title', $this->getTitle()->getPrefixedText() ) . "\n";