Fontconfig problem with one of the fonts

[franek.wiertara at onet.eu]

Hello,
This is my first post in this group.
I have installed TexLive in Dec last year; that is the ver. "tlmgr revision 57119 (2020-12-13 00:40:00 +0100)". I also run Ubuntu 20.04.
According to "3.4.4 System font configuration for XeTeX and LuaTeX" on "The TeX Live Guide—2020", we are supposed to add a font file "texlive/2020/texmf-var/fonts/conf/texlive-fontconfig.conf" to "/etc/fonts/conf.d/" and rename it as "09-texlive.conf". I simply the file to its source.
It turns out after doing so, I have started having issues with `snap` and `fontconfig`. I have currently snap 2.48.2 and snapd 2.48.2 installed. The errors are following:
 
error: cannot perform the following tasks:
- Run configure hook of "zoom-client" snap if present (run hook "configure":
-----
Fontconfig warning: "/etc/fonts/fonts.conf", line 5: unknown element "its:rules"
Fontconfig warning: "/etc/fonts/fonts.conf", line 6: unknown element "its:translateRule"
Fontconfig error: "/etc/fonts/fonts.conf", line 6: invalid attribute 'translate'
Fontconfig error: "/etc/fonts/fonts.conf", line 6: invalid attribute 'selector'
Fontconfig error: "/etc/fonts/fonts.conf", line 7: invalid attribute 'xmlns:its'
Fontconfig error: "/etc/fonts/fonts.conf", line 7: invalid attribute 'version'
Fontconfig warning: "/etc/fonts/fonts.conf", line 9: unknown element "description"
-----)
 
This is only one application but errors are caused by any application which need to be installed or refreshed by snap. If I remove "09-texlive.conf" and re-cache all fonts:
rm -f ~/.cache/fontconfig/*
sudo rm -f /var/cache/fontconfig/*
sudo fc-cache -rv
 
snap gets working again.
 
Is it possible that the font I have mentioned is not compatible with the new version of fontconfig? Ubuntu 20.04 has updated the library to the following:
 
 
$ dpkg -l | grep fontconfig
ii  fontconfig                                    2.13.1-2ubuntu3                       amd64        generic font configuration library - support binaries
ii  fontconfig-config                             2.13.1-2ubuntu3                       all          generic font configuration library - configuration
ii  libfontconfig1:amd64                          2.13.1-2ubuntu3                       amd64        generic font configuration library - runtime
 
Thanks
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