fatal error: json/json.h: No such file or directory #include <json/json.h>
Solution:
1. First check whether the file exists
If the file is found, the path to the file is written to the error file.
Then compiling again will be fine.
2. If the file does not exist, download the relevant file.
sudo apt-get install libjsoncpp-dev
sudo ln -s /usr/include/jsoncpp/json/ /usr/include/json