Não é possível compilar bibliografia no texmaker

Question

estou tentando escrever minha tese mas não consigo compilar a bibliografia, estes são os pacotes e a sintaxe que usei. A mensagem de erro que recebo é:

Citação 'xxx' na página 'nnn' indefinida

Como posso corrigir esse problema? Estou usando um arquivo .bib com todas as referências listadas lá.

\documentclass[a4paper, 12pt, twoside]{book}
%
\begin{filecontents*}[overwrite]{\jobname.xmpdata}
    \Title{Master Thesis: bla bla}
    \Author{Myself}
    \Language{en-GB}
    \Subject{...}
    \Keywords{...\sep}
\end{filecontents*}
%
\usepackage[UKenglish]{babel}
\usepackage{colorprofiles}
\usepackage[a-2b,mathxmp]{pdfx}[2018/12/22]
\hypersetup{pdfstartview=}
\usepackage[utf8]{inputenc}
\usepackage{appendix}
\usepackage{titlesec}
\usepackage[a4paper, top=2.5cm, bottom=2cm, right=2cm, left=2cm, bindingoffset=0.9cm, centering]{geometry}
\usepackage{graphicx}
\usepackage{wrapfig}
\usepackage{setspace}
\usepackage{xmpincl}
\usepackage{upgreek}
\usepackage{multirow}
\usepackage{subcaption}
\usepackage{longtable}
\usepackage{hyperref}
\usepackage{textcomp}
\usepackage{ragged2e}
\usepackage{enumitem}
\usepackage{amsmath}
\usepackage[T1]{fontenc}
\usepackage{booktabs}
\usepackage{csquotes}
\usepackage[backend=biber,style=authoryear,]{biblatex} % <<<----- my biblography style
\addbibresource{06_references.bib}
\usepackage{fancyhdr}
\usepackage{tabularx}
\usepackage{float}
\usepackage{caption}
\captionsetup{font=small}
%
\begin{document}

\onehalfspacing
\input{titlepage}
\thispagestyle{empty}

\frontmatter

\pagenumbering{Roman}
\setcounter{page}{3}

\pagestyle{fancy}
\fancyhead{}
\renewcommand{\chaptermark}[1]{%
\markboth{\thechapter.\ #1}{}}
\fancyhead[RO,LE]{\nouppercase{\textit{\leftmark}}}

\chapter*{Abstract}
\label{chap:abstract}
\input{00_abstract}

\addcontentsline{toc}{chapter}{\nameref{chap:abstract}}
\tableofcontents

\mainmatter

\chapter{Introduction}  
\input{01_introduction}

\chapter{Aim of the thesis} 
\input{02_aim}

\chapter{Materials and methods} 
\input{03_materials}

\chapter{Results and discussion} 
\input{04_results}

\chapter{Conclusions}  
\input{05_conclusions}

\begingroup % <<<------ my bibliography is here
\setstretch{1}
\setlength\bibitemsep{5pt}
\printbibliography[heading=bibintoc,title={References}]
\endgroup

\end{document}