由于某种原因，使用footlineqrcode中的包beamer会产生无效的二维码。
\documentclass{beamer}
\usepackage{qrcode}
\newcommand{\insertqrcode}{%
\qrcode{http://www.ctan.org}
}
% Add qrcode to footline
\setbeamertemplate{footline}{\insertqrcode}
% Same result
%\defbeamertemplate*{footline}{qrcode}{\insertqrcode}
%\setbeamertemplate{footline}[qrcode]
\begin{document}
\begin{frame}
\qrcode{http://www.ctan.org}
\insertqrcode
\end{frame}
\end{document}
如您所见，高度被拉伸，从而生成了无效的二维码。
*File List*
beamer.cls 2017/01/23 v3.41 A class for typesetting presentations
etoolbox.sty 2017/01/02 v2.4 e-TeX tools for LaTeX (JAW)
beamerbasemodes.sty
beamerbasedecode.sty
ifpdf.sty 2017/03/15 v3.2 Provides the ifpdf switch
beamerbaseoptions.sty
keyval.sty 2014/10/28 v1.15 key=value parser (DPC)
geometry.sty 2010/09/12 v5.6 Page Geometry
ifvtex.sty 2016/05/16 v1.6 Detect VTeX and its facilities (HO)
ifxetex.sty 2010/09/12 v0.6 Provides ifxetex conditional
size11.clo 2014/09/29 v1.4h Standard LaTeX file (size option)
pgfcore.sty 2010/04/11 v3.0.1a (rcs-revision 1.7)
graphicx.sty 2014/10/28 v1.0g Enhanced LaTeX Graphics (DPC,SPQR)
graphics.sty 2016/10/09 v1.0u Standard LaTeX Graphics (DPC,SPQR)
trig.sty 2016/01/03 v1.10 sin cos tan (DPC)
graphics.cfg 2016/06/04 v1.11 sample graphics configuration
pdftex.def 2017/01/12 v0.06k Graphics/color for pdfTeX
infwarerr.sty 2016/05/16 v1.4 Providing info/warning/error messages (HO)
ltxcmds.sty 2016/05/16 v1.23 LaTeX kernel commands for general use (HO)
pgfsys.sty 2014/07/09 v3.0.1a (rcs-revision 1.48)
pgfrcs.sty 2015/08/07 v3.0.1a (rcs-revision 1.31)
everyshi.sty 2001/05/15 v3.00 EveryShipout Package (MS)
pgfrcs.code.tex
pgfsys.code.tex
pgfsyssoftpath.code.tex 2013/09/09 (rcs-revision 1.9)
pgfsysprotocol.code.tex 2006/10/16 (rcs-revision 1.4)
xcolor.sty 2016/05/11 v2.12 LaTeX color extensions (UK)
color.cfg 2016/01/02 v1.6 sample color configuration
pgfcore.code.tex
xxcolor.sty 2003/10/24 ver 0.1
atbegshi.sty 2016/06/09 v1.18 At begin shipout hook (HO)
hyperref.sty 2017/03/14 v6.85a Hypertext links for LaTeX
hobsub-hyperref.sty 2016/05/16 v1.14 Bundle oberdiek, subset hyperref (HO)
hobsub-generic.sty 2016/05/16 v1.14 Bundle oberdiek, subset generic (HO)
hobsub.sty 2016/05/16 v1.14 Construct package bundles (HO)
ifluatex.sty 2016/05/16 v1.4 Provides the ifluatex switch (HO)
intcalc.sty 2016/05/16 v1.2 Expandable calculations with integers (HO)
etexcmds.sty 2016/05/16 v1.6 Avoid name clashes with e-TeX commands (HO)
kvsetkeys.sty 2016/05/16 v1.17 Key value parser (HO)
kvdefinekeys.sty 2016/05/16 v1.4 Define keys (HO)
pdftexcmds.sty 2017/03/19 v0.25 Utility functions of pdfTeX for LuaTeX (HO)
pdfescape.sty 2016/05/16 v1.14 Implements pdfTeX's escape features (HO)
bigintcalc.sty 2016/05/16 v1.4 Expandable calculations on big integers (HO)
bitset.sty 2016/05/16 v1.2 Handle bit-vector datatype (HO)
uniquecounter.sty 2016/05/16 v1.3 Provide unlimited unique counter (HO)
letltxmacro.sty 2016/05/16 v1.5 Let assignment for LaTeX macros (HO)
hopatch.sty 2016/05/16 v1.3 Wrapper for package hooks (HO)
xcolor-patch.sty 2016/05/16 xcolor patch
atveryend.sty 2016/05/16 v1.9 Hooks at the very end of document (HO)
refcount.sty 2016/05/16 v3.5 Data extraction from label references (HO)
hycolor.sty 2016/05/16 v1.8 Color options for hyperref/bookmark (HO)
auxhook.sty 2016/05/16 v1.4 Hooks for auxiliary files (HO)
kvoptions.sty 2016/05/16 v3.12 Key value format for package options (HO)
pd1enc.def 2017/03/14 v6.85a Hyperref: PDFDocEncoding definition (HO)
hyperref.cfg 2002/06/06 v1.2 hyperref configuration of TeXLive
url.sty 2013/09/16 ver 3.4 Verb mode for urls, etc.
hpdftex.def 2017/03/14 v6.85a Hyperref driver for pdfTeX
rerunfilecheck.sty 2016/05/16 v1.8 Rerun checks for auxiliary files (HO)
beamerbaserequires.sty
beamerbasecompatibility.sty
beamerbasefont.sty
amssymb.sty 2013/01/14 v3.01 AMS font symbols
amsfonts.sty 2013/01/14 v3.01 Basic AMSFonts support
sansmathaccent.sty 2013/03/28
filehook.sty 2011/10/12 v0.5d Hooks for input files
beamerbasetranslator.sty
translator.sty 2010/06/12 ver 1.10
translator-language-mappings.tex
beamerbasemisc.sty
beamerbasetwoscreens.sty
beamerbaseoverlay.sty
beamerbasetitle.sty
beamerbasesection.sty
beamerbaseframe.sty
beamerbaseverbatim.sty
beamerbaseframesize.sty
beamerbaseframecomponents.sty
beamerbasecolor.sty
beamerbasenotes.sty
beamerbasetoc.sty
beamerbasetemplates.sty
beamerbaseauxtemplates.sty
beamerbaseboxes.sty
beamerbaselocalstructure.sty
enumerate.sty 2015/07/23 v3.00 enumerate extensions (DPC)
beamerbasenavigation.sty
beamerbasetheorems.sty
amsmath.sty 2016/11/05 v2.16a AMS math features
amstext.sty 2000/06/29 v2.01 AMS text
amsgen.sty 1999/11/30 v2.0 generic functions
amsbsy.sty 1999/11/29 v1.2d Bold Symbols
amsopn.sty 2016/03/08 v2.02 operator names
amsthm.sty 2015/03/04 v2.20.2
beamerbasethemes.sty
beamerthemedefault.sty
beamerfontthemedefault.sty
beamercolorthemedefault.sty
beamerinnerthemedefault.sty
beamerouterthemedefault.sty
qrcode.sty 2015/01/08 v1.51 QR code generation
xkeyval.sty 2014/12/03 v2.7a package option processing (HA)
xkeyval.tex 2014/12/03 v2.7a key=value parser (HA)
supp-pdf.mkii
epstopdf-base.sty 2016/05/15 v2.6 Base part for package epstopdf
grfext.sty 2016/05/16 v1.2 Manage graphics extensions (HO)
epstopdf-sys.cfg 2010/07/13 v1.3 Configuration of (r)epstopdf for TeX Live
nameref.sty 2016/05/21 v2.44 Cross-referencing by name of section
gettitlestring.sty 2016/05/16 v1.5 Cleanup title references (HO)
aaa.out
aaa.out
translator-basic-dictionary-English.dict
translator-bibliography-dictionary-English.dict
translator-environment-dictionary-English.dict
translator-months-dictionary-English.dict
translator-numbers-dictionary-English.dict
translator-theorem-dictionary-English.dict
umsa.fd 2013/01/14 v3.01 AMS symbols A
umsb.fd 2013/01/14 v3.01 AMS symbols B
ot1mathkerncmss.fd 2013/03/27 Fontinst v1.933 font definitions for OT1/mathk
erncmss.
***********
答案1
好吧，在使用我当前的 MiKTeX 2.9 编译您的代码后，我没有看到任何错误消息，并且生成的 pdf 中也没有错误。我添加了\listfiles第一个命令来获取日志文件中使用的软件包和版本号的列表：
*File List*
beamer.cls 2018/12/02 v3.55 A class for typesetting presentations
beamerbasemodes.sty
etoolbox.sty 2018/08/19 v2.5f e-TeX tools for LaTeX (JAW)
beamerbasedecode.sty
ifpdf.sty 2018/09/07 v3.3 Provides the ifpdf switch
beamerbaseoptions.sty
keyval.sty 2014/10/28 v1.15 key=value parser (DPC)
geometry.sty 2018/04/16 v5.8 Page Geometry
ifvtex.sty 2016/05/16 v1.6 Detect VTeX and its facilities (HO)
ifxetex.sty 2010/09/12 v0.6 Provides ifxetex conditional
geometry.cfg
size11.clo 2018/09/03 v1.4i Standard LaTeX file (size option)
pgfcore.sty 2019/04/04 v3.1.2 (3.1.2)
graphicx.sty 2017/06/01 v1.1a Enhanced LaTeX Graphics (DPC,SPQR)
graphics.sty 2017/06/25 v1.2c Standard LaTeX Graphics (DPC,SPQR)
trig.sty 2016/01/03 v1.10 sin cos tan (DPC)
graphics.cfg 2016/06/04 v1.11 sample graphics configuration
pdftex.def 2018/01/08 v1.0l Graphics/color driver for pdftex
pgfsys.sty 2019/04/04 v3.1.2 (3.1.2)
pgfrcs.sty 2019/04/04 v3.1.2 (3.1.2)
everyshi.sty 2001/05/15 v3.00 EveryShipout Package (MS)
pgfrcs.code.tex
pgfsys.code.tex
pgfsyssoftpath.code.tex 2019/04/04 v3.1.2 (3.1.2)
pgfsysprotocol.code.tex 2019/04/04 v3.1.2 (3.1.2)
xcolor.sty 2016/05/11 v2.12 LaTeX color extensions (UK)
color.cfg 2016/01/02 v1.6 sample color configuration
pgfcore.code.tex
xxcolor.sty 2003/10/24 ver 0.1
atbegshi.sty 2016/06/09 v1.18 At begin shipout hook (HO)
infwarerr.sty 2016/05/16 v1.4 Providing info/warning/error messages (HO)
ltxcmds.sty 2016/05/16 v1.23 LaTeX kernel commands for general use (HO)
hyperref.sty 2018/11/30 v6.88e Hypertext links for LaTeX
hobsub-hyperref.sty 2016/05/16 v1.14 Bundle oberdiek, subset hyperref (HO)
hobsub-generic.sty 2016/05/16 v1.14 Bundle oberdiek, subset generic (HO)
hobsub.sty 2016/05/16 v1.14 Construct package bundles (HO)
ifluatex.sty 2016/05/16 v1.4 Provides the ifluatex switch (HO)
intcalc.sty 2016/05/16 v1.2 Expandable calculations with integers (HO)
etexcmds.sty 2016/05/16 v1.6 Avoid name clashes with e-TeX commands (HO)
kvsetkeys.sty 2016/05/16 v1.17 Key value parser (HO)
kvdefinekeys.sty 2016/05/16 v1.4 Define keys (HO)
pdftexcmds.sty 2018/09/10 v0.29 Utility functions of pdfTeX for LuaTeX (HO)
pdfescape.sty 2016/05/16 v1.14 Implements pdfTeX's escape features (HO)
bigintcalc.sty 2016/05/16 v1.4 Expandable calculations on big integers (HO)
bitset.sty 2016/05/16 v1.2 Handle bit-vector datatype (HO)
uniquecounter.sty 2016/05/16 v1.3 Provide unlimited unique counter (HO)
letltxmacro.sty 2016/05/16 v1.5 Let assignment for LaTeX macros (HO)
hopatch.sty 2016/05/16 v1.3 Wrapper for package hooks (HO)
xcolor-patch.sty 2016/05/16 xcolor patch
atveryend.sty 2016/05/16 v1.9 Hooks at the very end of document (HO)
refcount.sty 2016/05/16 v3.5 Data extraction from label references (HO)
hycolor.sty 2016/05/16 v1.8 Color options for hyperref/bookmark (HO)
auxhook.sty 2016/05/16 v1.4 Hooks for auxiliary files (HO)
kvoptions.sty 2016/05/16 v3.12 Key value format for package options (HO)
pd1enc.def 2018/11/30 v6.88e Hyperref: PDFDocEncoding definition (HO)
hyperref.cfg 2002/06/06 v1.2 hyperref configuration of TeXLive
url.sty 2013/09/16 ver 3.4 Verb mode for urls, etc.
hpdftex.def 2018/11/30 v6.88e Hyperref driver for pdfTeX
rerunfilecheck.sty 2016/05/16 v1.8 Rerun checks for auxiliary files (HO)
beamerbaserequires.sty
beamerbasecompatibility.sty
beamerbasefont.sty
amssymb.sty 2013/01/14 v3.01 AMS font symbols
amsfonts.sty 2013/01/14 v3.01 Basic AMSFonts support
sansmathaccent.sty 2013/03/28
filehook.sty 2011/10/12 v0.5d Hooks for input files
beamerbasetranslator.sty
translator.sty 2018/01/04 v1.12 Easy translation of strings in LaTeX
beamerbasemisc.sty
beamerbasetwoscreens.sty
beamerbaseoverlay.sty
beamerbasetitle.sty
beamerbasesection.sty
beamerbaseframe.sty
beamerbaseverbatim.sty
beamerbaseframesize.sty
beamerbaseframecomponents.sty
beamerbasecolor.sty
beamerbasenotes.sty
beamerbasetoc.sty
beamerbasetemplates.sty
beamerbaseauxtemplates.sty
beamerbaseboxes.sty
beamerbaselocalstructure.sty
enumerate.sty 2015/07/23 v3.00 enumerate extensions (DPC)
beamerbasenavigation.sty
beamerbasetheorems.sty
amsmath.sty 2018/12/01 v2.17b AMS math features
amstext.sty 2000/06/29 v2.01 AMS text
amsgen.sty 1999/11/30 v2.0 generic functions
amsbsy.sty 1999/11/29 v1.2d Bold Symbols
amsopn.sty 2016/03/08 v2.02 operator names
amsthm.sty 2017/10/31 v2.20.4
beamerbasethemes.sty
beamerthemedefault.sty
beamerfontthemedefault.sty
beamercolorthemedefault.sty
beamerinnerthemedefault.sty
beamerouterthemedefault.sty
qrcode.sty 2015/01/08 v1.51 QR code generation
xkeyval.sty 2014/12/03 v2.7a package option processing (HA)
xkeyval.tex 2014/12/03 v2.7a key=value parser (HA)
supp-pdf.mkii
epstopdf-base.sty 2016/05/15 v2.6 Base part for package epstopdf
grfext.sty 2016/05/16 v1.2 Manage graphics extensions (HO)
nameref.sty 2016/05/21 v2.44 Cross-referencing by name of section
gettitlestring.sty 2016/05/16 v1.5 Cleanup title references (HO)
487409.out
487409.out
translator-basic-dictionary-English.dict
translator-bibliography-dictionary-English.dict
translator-environment-dictionary-English.dict
translator-months-dictionary-English.dict
translator-numbers-dictionary-English.dict
translator-theorem-dictionary-English.dict
umsa.fd 2013/01/14 v3.01 AMS symbols A
umsb.fd 2013/01/14 v3.01 AMS symbols B
ot1mathkerncmss.fd 2013/03/27 Fontinst v1.933 font definitions for OT1/mathkerncmss.
***********
得到的pdf是：
请添加\listfiles到您的mwe.tex并编译（请使用您问题中给出的 mwe 来获得可以与我的结果进行比较的结果！）。然后将结果中使用的软件包和版本号列表与我的进行比较。我猜您有一些较旧的版本...您是否考虑过更新您的系统（如果您的时间紧迫，请不要这样做！）？