No i face palmed you because you think a currency is written in php. I did read amd he clearly says java. Php is for the output. Obviously you cant wrote a fork and node in php. Most use c++ I think you can use java bit he is talking about a java kernal. This display error just means the target can ot be found in the specific directory. You see thst error alot when you stsrt making website interfaces. For a normal page you will just use .html not .php so if you want to use an api you have to have a .php