Thank you for your advice.
I am working on building the Legato.cwe file in parallel with investigating the cause of the crash.
I built it with Ubuntu 18.04.06 LTS and got the same error as Make wp76xx error.
I was able to work around this by installing the following package.
sudo apt-get install libtool
sudo apt-get install cmake
sudo apt-get install autoconf-archive
sudo apt-get install pkg-config
sudo apt-get install flex
sudo apt-get install bison
sudo apt-get install byacc
sudo apt-get install gperf
sudo apt-get install libncurses-dev
I have confirmed that I can build normally, but when I change the wifi.sdef as you advised as follows, I get the error.
/home/systemac/.leaf/wp76-legato_19.02.0-201903211732/apps/sample/modemDemo/demoComponent/Component.cdef:17:15: error: Couldn't find file 'send_util.api'.
Makefile:605: recipe for target 'system' failed
Could you please tell me how to resolve this error?