Angular 9 - NGCC fails with an unhandled exception

Question

Buidling the application after having upgraded dependcies to Angular 9 (and having performed necessary code changes) throws an error:

Compiling @ang

Answer 1

This issue is becuase you might be running your app on any port and angular ngcc was assigned with a particular process id which was specified and locked in a file called __ngcc_lock_file__ inside \node_modules\@angular\compiler-cli\ngcc. If you are doing a hard system turn off or if your os crashed, this lock file will be there in the node_modules. And once you turn on you machine and trying to start the application again, angular cli will check this lock file and trying to find the process id specified in the file. Most of the time that process id will be missing since you did a complete machine restart and it will throw the this error.

Solution 1. remove node_modules and do npm install

Solution 2. Smart solution - delete the lock file as below.

Go to `\node_modules\@angular\compiler-cli\ngcc`

find the file named __ngcc_lock_file__ delete it. Done.

Happy hacking