# pdf/a - validation problem - The F key is missing

I tried to convert my thesis from Latex to required pdf/a - version 2u. However, two problem occured from a validation test.

Firt one: "The key F is required but missing."
I failed with googling it, i think that it has maybe something to do with links. I came across one forum, but I do not understand (probably they are not working in LaTeX) - https://forums.adobe.com/thread/1023316
Then, I tried to find the sollution on our forum, but no one had really the same problem. E.g. I tried to use sollution from this post PDF/A with hyperref on TeX Live 2013, but the validator told me, that I have pdf1.4, not even pdf/A.
Does anybody know, what should I change to get rid of this "F key" or how to deal with it?

Second problem, which is probably not so important: The document contains hidden, invisible, non-viewable or non-printable annotations.
I don't know, what they mean by that exactly. Is there a problem with my notes (meaning text starting with %). Does anybody know the sollution?

My code in preambule, packages used are at the end:

``````    \documentclass[openany,hidelinks]{book}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[czech]{babel}
\usepackage{fancyhdr}
\usepackage{float}

\usepackage{graphicx}
\usepackage{amsmath,amssymb,amsthm}
\usepackage{color}
\usepackage[round]{natbib}
\usepackage{hyperref}
\usepackage{bookmark}
\usepackage[normalem]{ulem}

\newcommand{\myand}{\&\ }

\usepackage[acronym]{glossaries}
\makeglossaries

\useunder{\uline}{\ul}{}
\numberwithin{equation}{chapter}

\usepackage{longtable}
\usepackage{array}
\usepackage{regexpatch}
\makeatletter
\xpatchparametertext\@cline{-}{\cA-}{}{}
\usepackage{placeins}
\usepackage{booktabs}
\usepackage{caption}

\usepackage{pdfpages}

%for pdfA
\usepackage{xmpincl}
\usepackage[a-2u]{pdfx}
\usepackage{lmodern}
\usepackage{textcomp}
``````

I would be very grateful for every answer! :) Thank you.

The problem is with my bibliography! Another validator gave me exact pages of the problems. And it looks like this: `root/document[0]/pages[54](825 0 obj PDPage)/annots[16](821 0 obj PDAnnot)`
Second error has this description:
`root/document[0]/pages[64](935 0 obj PDPage)/contentStream[0](936 0 objPDContentStream)/operators[556]/font[0](BCVKHY+LMMathSymbols10-Regular)`

`root/document[0]/pages[64](935 0 obj PDPage)/contentStream[0](936 0 objPDContentStream)/operators[611]/font[0](HVVRCK+LMMathSymbols7-Regular)`

• It is impossible to debug something like this without a complete example -- and when you have a complete example you should make an effort to make a small complete example. – Ulrike Fischer May 10 '18 at 17:58
• @UlrikeFischer I am very sorry, but I do not know what you mean by example, example of what if not of the code. Thanks :) – Lenka Tom May 10 '18 at 18:01
• @UlrikeFischer I have edited my post, i hope that I did it the way you meant – Lenka Tom May 10 '18 at 19:12
• Add option`pdfa` to package `hyperref`. The option adds some few warnings and settings for greater compliance to PDF/A. It also sets the `/F` key in link annotations. – Heiko Oberdiek May 10 '18 at 19:15
• @HeikoOberdiek Wow, it helped! The main error is gone, thank you a lot! :) – Lenka Tom May 10 '18 at 19:35

## 1 Answer

It is sufficent to add option `pdfa` to package `hyperref`. (as suggested by @heikooberdiek)