Fresh install of pi, tested and MM runs. Added the modules I want, tested, they all load and everything works. Ran updates on the pi, rebooted, MM won’t load.

PM2 log files show:

Error: ENOENT: no such file or directory, open 'package.json'
    at Object.fs.openSync (fs.js:660:18)
    at Object.fs.readFileSync (fs.js:565:33)
    at Object.<anonymous> (/home/pi/MagicMirror/js/app.js:15:32)
    at Module._compile (internal/modules/cjs/loader.js:654:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:665:10)
    at Module.load (internal/modules/cjs/loader.js:566:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:506:12)
    at Function.Module._load (internal/modules/cjs/loader.js:498:3)
    at Module.require (internal/modules/cjs/loader.js:598:17)
    at require (internal/modules/cjs/helpers.js:11:18)

That log repeats as long as PM2 tries to keep loading MM.

running
find . -name package.json -maxdepth 2 -execdir npm install \;
doesn’t fix it.

MM files are up to date (git pull), and the config file is good (npm run config:check)

Not sure where to go from here.