# Dimension too large after recent longtable update

After recent update of longtable package (2021.05.07) I am getting the error:

Dimension too large. \end{longtabu}


Log:

! Dimension too large.
=
l.10 \end{longtabu}

I can't work with sizes bigger than about 19 feet.
Continue and I'll use the largest value I can.


MWE:

\documentclass{article}
\usepackage{longtable}%
\usepackage{tabu}%
\begin{document}
\begin{longtabu}  {llX}
a & b & c\\
\end{longtabu}
\end{document}

• Coincidentally, I had an issue with tabu package today. Ulrike said it's broken. ref – Book Of Flames Jun 10 at 14:53
• The problem is that longtable is actively maintained to fix issues; on the other hand, tabu has been buggy forever and unmaintained for several years. – egreg Jun 10 at 14:58
• you probably also updated latex. tabu does lots of low-level tricks and every change in latex can make it fail in more places. Sorry but since years the advice is not to use this package, see the readme here github.com/tabu-issues-for-future-maintainer/tabu. – Ulrike Fischer Jun 10 at 15:38
• I just tried 4.14,4.15 and 4.16 and tabu fails with all of them which is more understandable 4.14 had some re-organisation to cope with floats appearing on the same page (when older versions would run off the bottom of the page in some cases) – David Carlisle Jun 10 at 16:34
• Ulrike found that tabu was relying on me using box1 and failds now I allocate a longtable-specific box (to avoid clashes with other packages....) github.com/tabu-issues-for-future-maintainer/tabu/issues/26 – David Carlisle Jun 10 at 19:58

tabu is unmaintained but as a short term fix you can force an old version of longtable to load

\documentclass{article}
\usepackage{longtable}[=v4.13]%
\usepackage{tabu}%
\begin{document}

\begin{longtabu}  {llX}
a & b & c\\
\end{longtabu}
\end{document}


The changes in longtable have been very minor and only addressing features that fairly obviously needed addressing, but apparently tabu was relying on an internal definition somewhere.

It turns out that specifically tabu is relying on longtable using the \box1 scratch register and fails now longtable allocates a box for its internal use (a change made to avoid conflicts with other packages, you can't win...) there is a patch at the tabu github

https://github.com/tabu-issues-for-future-maintainer/tabu/issues/26

The new LaTeX3 package tabularray is an alternative to the outdated tabu package. You can use tblr and longtblr environments with it.

\documentclass{article}
\usepackage{tabularray}
\begin{document}
\begin{longtblr}[
caption = {Table Caption},
]{llX[2,c]X[3,r]}
\hline
a & b & c & d \\
\hline
\end{longtblr}
\end{document}