TOC not generated with imakeidx and Reledpar

Question

I am typesetting a book with verses in three languages. The verses are typeset to appear in three columns using Reledpar. I also need three different indexes of these verses in the three languages, so I am using imakeidx to generate these.

However, TOC is not getting generated for my book. After many trials, I found that the problem is with Reledpar. If I remove this package, both TOC and imakeidx work perfectly. As soon as I introduce Reledpar, this is the error I get

No file testing_multiple_index.toc. ! No room for a new \write. \e@ch@ck ...message {No room for a new \string #4} \fi \fi l.24 ^^I\tableofcontents ?

Here is a MWE

\documentclass[12 pt, twoside]{extbook} %extarticle provides additional font-sizes



%for index
\usepackage{imakeidx}
\makeindex
\makeindex[name=eng,title=Alphabetical Index of Verses]
\makeindex[name=dev,title=Index of verses]


%parallel typesetting
\usepackage{reledmac}
\usepackage[shiftedpstarts]{reledpar}
\numberlinefalse
\setgoalfraction{0.8} % for reledpar error in finishing pages


\begin{document}


\frontmatter

\tableofcontents

\mainmatter
\chapter {Chapter 1}

\section {Section A}

    This is a test line. \index[eng]{a verse}
    This is a test line. 
    This is a test line. \index[dev]{sanskrit verse}
    This is a test line. 
    This is a test line. 

\section {Section B}
    This is a test line. \index[eng]{another verse}
    This is a test line. 
    This is a test line. 
    This is a test line. \index[dev]{sanskrit verse 2}
    This is a test line. 



\backmatter


\printindex[eng]
\printindex[dev]



\end{document}

Answer 1

As explained by ShreevatsaR you can use morewrites package.

But before doing that:

1. As explained in reledmac handbook, you must respect this order
   1. Load imakeidx
   2. Load reledmac
   3. Declare your index.

The order is very important.

Last but not least: if you don't use the endnotes / eledsection tools of reledmac, use noeledsec and noend optiions when loading eledmac. You will get better results, and you should solve your No room for a new \write and consequently solve your bug without morewritespackage. You could also use one of the "performance option" described in § 4.2 of reledmac handbook.

Ps : there is a § "No room for a new"… in reledmac handbook