lyx file from 2015 not converted to pdf

[Wolfgang Engelmann]

Am 24.03.20 um 20:24 schrieb Jean-Marc Lasgouttes:
> Le 24/03/2020 à 20:23, Wolfgang Engelmann a écrit :
> 
>>> What does Help>About>Information on Compilation say? It should tell 
>>> us what options where active when configuring LyX.
> 
>> LyX Version 2.3.4.2
>> (Friday, February 7, 2020)
>>
>> Library directory: /usr/share/lyx/
>> User directory: ~/.lyx/
>> Qt Version (run-time): 5.12.5
>> Qt Version (compile-time): 5.12.5
> 
> This is the first tab of the dialog. I am interested by the 4th one.
> 
> JMarc
> 
Here it is:
Build Info:
LyX 2.3.4.2 (2020-02-07)
Configuration
   Host type:               x86_64-pc-linux-gnu
   Special build flags:      build=release std-regex warnings use-enchant
   Bundled libraries:       (none)
   C++ Compiler:            g++ (9.2.1)
   C++ Compiler flags:       -Wall -Wextra -Wno-deprecated-copy -fPIC 
-O2 -std=c++14
   C++ Compiler user flags:  -Wdate-time -D_FORTIFY_SOURCE=2 -std=c++14 
-g -O2 -fdebug-prefix-map=/build/lyx-Jf4jAS/lyx-2.3.4.2=. 
-fstack-protector-strong -Wformat -Werror=format-security -fPIC
   Linker flags:
   Linker user flags:       -Wl,-z,defs -Wl,--as-needed -Wl,-z,relro 
-Wl,-z,now
   Qt Frontend:
       Qt version:	   5.12.5
   Packaging:               posix
   LyX binary dir:          /usr/bin
   LyX files dir:           /usr/share/lyx

Wolfgang