Problem to build app

Error: Type AboutPage in D:/radioencuentro/src/pages/about/about.ts is part of the declarations of 2 modules: AppModule in D:/radioencuentro/src/app/app.module.ts and AboutPageModule in D:/radioencuentro/src/pages/about/about.module.ts! Please consider moving AboutPage in D:/radioencuentro/src/pages/about/about.ts to a higher module that imports AppModule in D:/radioencuentro/src/app/app.module.ts and AboutPageModule in D:/radioencuentro/src/pages/about/about.module.ts. You can also create a new NgModule that exports and includes AboutPage in D:/radioencuentro/src/pages/about/about.ts then import that NgModule in AppModule in D:/radioencuentro/src/app/app.module.ts and AboutPageModule in D:/radioencuentro/src/pages/about/about.module.ts.
at Error (native)
at syntaxError (D:\radioencuentro\node_modules@angular\compiler\bundles\compiler.umd.js:1550:34)
at CompileMetadataResolver._addTypeToModule (D:\radioencuentro\node_modules@angular\compiler\bundles\compiler.umd.js:14655:31)
at D:\radioencuentro\node_modules@angular\compiler\bundles\compiler.umd.js:14543:27
at Array.forEach (native)
at CompileMetadataResolver.getNgModuleMetadata (D:\radioencuentro\node_modules@angular\compiler\bundles\compiler.umd.js:14534:54)
at addNgModule (D:\radioencuentro\node_modules@angular\compiler\bundles\compiler.umd.js:23050:58)
at D:\radioencuentro\node_modules@angular\compiler\bundles\compiler.umd.js:23061:14
at Array.forEach (native)
at _createNgModules (D:\radioencuentro\node_modules@angular\compiler\bundles\compiler.umd.js:23060:26)

Are you using lazy loading?

Yes, delete AboutPage from your app.modules.ts
No, delete AboutPageModule