Must use import to load ES Module: /action/node_modules/conventional-changelog-angular/src/index.js require() of ES modules is not supported. require() of /action/node_modules/conventional-changelog-angular/src/index.js from /action/src/validateTitle.js is an ES module file as it is a .js file whose nearest parent package.json contains "type": "module" which defines all .js files in that package scope as ES modules. Instead rename index.js to end in .cjs, change the requiring code to use import(), or remove "type": "module" from /action/node_modules/conventional-changelog-angular/package.json.