Paragraph ended before � was complete. } and Argument of � has an extra }. } --can't fix

Question

I am getting these error for my following preamble file. I can't figure out what is causing the error.

'''

\documentclass{article}
%%%%%%%% CREATE DOCUMENT STRUCTURE %%%%%%%%
%% Language and font encodings
\usepackage[english]{babel}
\usepackage[utf8x]{inputenc}
\usepackage[T1]{fontenc}
%\usepackage{subfig}
%% Sets page size and margins
\usepackage[a4paper,top=3cm,bottom=2cm,left=2cm,right=2cm,marginparwidth=2cm]{geometry}
%% Useful packages
\usepackage{amsmath}
\usepackage[colorlinks=true,linkcolor=blue,urlcolor=black,bookmarksopen=true]{hyperref}
\usepackage{bookmark}
\usepackage{wrapfig}
\usepackage{ragged2e}
\usepackage{siunitx}
\usepackage{pdfpages}
\usepackage{chngcntr}
\usepackage{sectsty}
\usepackage{graphicx}
\usepackage{amssymb}
\usepackage[colorinlistoftodos]{todonotes}
\usepackage{caption}
\usepackage{subcaption}
\usepackage{apacite}
\usepackage{fancyhdr}
\usepackage{booktabs}
\usepackage{float}
\usepackage{pgfplots}
\usepackage{titling} 
\usepackage{blindtext}
\usepackage[square,sort,comma,numbers]{natbib}
\usepackage[colorinlistoftodos]{todonotes}
\usepackage{xcolor}
\usepackage[export]{adjustbox}
\definecolor{darkgreen}{rgb}{0.0, 0.4, 0.0}
\renewcommand{\familydefault}{\rmdefault}
\usepackage{titlesec}
\titleformat*{\section}{\normalfont\Large\bfseries}
\titleformat*{\subsection}{\normalfont\large\bfseries}
\titleformat*{\subsubsection}{\normalfont\normalsize\bfseries}
%\titleformat*{\paragraph}{\normalfont\normalsize\bfseries}
\newcommand{\atan}{\tan^{-1}}
\hypersetup{
    pdfpagelabels=true,%
    plainpages=false,%
    pdfauthor={Bharat Aryal},%
    pdftitle={Title},%
    pdfsubject={Subject},%
    bookmarksnumbered=true,%
    colorlinks=false,%
    citecolor=black,%
    filecolor=black,%
    linkcolor=black,%you should probably change this to black before printing
    urlcolor=black,%
    pdfstartview=FitH
}

'''