"Unknown option `poster' for package `tcolorbox'" yet the library is loaded

Question

I am trying to use the poster library for the tcolorbox package, and, following the tcolorbox manual, I am loading this library via

   \usepackage[poster]{tcolorbox}

in the preamble. When I compile (pdflatex) I always get the following error:

   ! LaTeX Error: Unknown option `poster' for package `tcolorbox'.

I also tried to put the following line in my preamble

   \tcbuselibrary{poster}

which should be equivalent to the option in the above \usepackage statement (according to the tcolorbox manual). I get the following message:

   ! Package pgfkeys Error: I do not know the key '/tcb/library/poster' and I am going to ignore it. Perhaps you misspelled it.

No matter what combination of the two methods I try, I still get this type of error.

Finally I noticed there was no tcbposter.code.tex file in my texlive/texmf-dist/tex/latex/tcolorbox/ directory, and I thought this was the source of the error. So I downloaded it from this link and put it in this directory, but I still get the same error.

Here is a MWE (or rather MnotWE):

   \documentclass[12pt]{article}

   \usepackage[a3paper,landscape]{geometry}
   \usepackage[poster]{tcolorbox}
   \pagestyle{empty}

   \begin{document}
     \begin{tcbposter}[
     coverage = {spread},
     poster = {showframe,columns=4,rows=5},
     ]
     \end{poster}
   \end{document}

Why am I getting this error?

Answer 1

The poster library is a new feature of tcolorbox from version 4.10, dating back to 2017/07/05, the previous release 4.03 does not provide poster.

The Changes file from 4.10 clearly states at the end:

version 4.10 (2017/07/05)

• new options: 'inherit height', 'verbatim ignore percent'

• library 'skins' * new style 'enhanced standard jigsaw'

• library 'magazine': * new macro: '\ifboxarrayempty'

• library 'breakable': * option 'break at' allows negative values now.

• the algorithm for breaks inside a multicolumn environment was improved

  (user code may be affected by this change). * new macro: '\tcbbreak'

• library 'minted': * the default settings for 'minted options' are supplemented by 'breaklines,autogobble'

• new library 'poster' * new macros and environments: 'tcbposter', '\tcbposterset', '\posterbox', 'posterboxenv', 'tcbposterwidth', 'tcbposterheight', 'tcbpostercolspacing', 'tcbposterrowspacing', 'tcbpostercolumns', 'tcbposterrows', 'tcbpostercolwidth', 'tcbposterrowheight' * new options: 'poster', 'columns', 'rows', 'colspacing', 'rowspacing', 'spacing', 'showframe', 'width', 'height', 'prefix', 'coverage', 'no coverage', 'boxes', 'fontsize', 'name', 'column', 'column*', 'span', 'row', 'rowspan', 'fixed height', 'below', 'above', 'at', 'between', 'sequence', 'placeholder', 'xshift', 'yshift'

• New example file 'tcolorbox-example-poster'

• New tutorial 'tcolorbox-tutorial-poster' for poster creation

The corrected code

 \documentclass[12pt]{article}

 \usepackage[a3paper,landscape]{geometry}
 \usepackage[poster]{tcolorbox}
 \pagestyle{empty}

 \begin{document}
 \begin{tcbposter}[
   coverage = {spread},
   poster = {showframe,columns=4,rows=5},
   ]
 \end{tcbposter}
\end{document}

gives this output: