\mainmatter seems to sometimes force a blank page if the current contents (the place where \mainmatter is called) are on an odd numbered page. openany and oneside do not seem to work here. They only work when opening a new chapter, but not when the main matter starts.
I want to disable inserting of blank pages altogether even at the beginning of the main matter.
\documentclass[11pt, openany, oneside]{book}
\usepackage[a4paper]{geometry}
% BEGIN_FOLD
\geometry{twoside=false, showframe=false,inner=1.05in,outer=1.05in,includemp=true,asymmetric=true,bindingoffset=0mm,marginparsep=0mm, marginparwidth=0mm}
\geometry{bottom=0.9in,vmarginratio=3:5,includehead=true, includefoot=true,headheight=8pt, headsep=14pt,footskip=10.9mm}
% END_FOLD
\usepackage{blindtext}
\begin{document}
\blindtext
\tableofcontents
\clearpage
\blindtext
\mainmatter
\Blinddocument
\end{document}
asymetricoption do for you? Why are you including all those different options togeometry? In other words, why do you tell the package you do not want atwosidedocument, and later overwrite that stating you do wanttwoside? – Johannes_B Jul 01 '19 at 10:01asymetric=falseworks – Al-Motasem Aldaoudeyeh Jul 01 '19 at 10:10