Cant seem to build ionic 2 app in –prod

Question

I keep getting this error whenever I ionic build android --prod. it works fine with ionic serve and ionic run. even ionic build is okay.

Error: Cannot determine the module for class SupplierChequeModalPage in 
C:/wamp/www/pos/src/pages/supplier-cheque-modal/supplier-cheque
-modal.ts! Add SupplierChequeModalPage to the NgModule to fix it.
Cannot determine the module for class LetterAvatarDirective in 
C:/wamp/www/pos/src/directives/letter-avatar/letter-avatar.ts! Add Lette
rAvatarDirective to the NgModule to fix it.
Cannot determine the module for class ClientChequeModalPage in 
C:/wamp/www/pos/src/pages/client-cheque-modal/client-cheque-modal.ts! Ad
d ClientChequeModalPage to the NgModule to fix it.
Cannot determine the module for class CustomerModalPage in 
C:/wamp/www/pos/src/pages/customer-modal/customer-modal.ts! Add CustomerModa
lPage to the NgModule to fix it.
Cannot determine the module for class LowStockFilterPipe in 
C:/wamp/www/pos/src/pipes/low-stock-filter/low-stock-filter.ts! Add LowStoc
kFilterPipe to the NgModule to fix it.
Cannot determine the module for class DateFilterPipe in 
C:/wamp/www/pos/src/pipes/date-filter/date-filter.ts! Add DateFilterPipe to 
the NgModule to fix it. at Error (native) at syntaxError 
(C:\wamp\www\pos\node_modules\@angular\compiler\bundles\compiler.umd.js:
1550:34) at analyzeAndValidateNgModules 
(C:\wamp\www\pos\node_modules\@angular\compiler\bundles\compiler.umd.js:
22948:15) at AotCompiler.compileAll 
(C:\wamp\www\pos\node_modules\@angular\compiler\bundles\compiler.umd.js:
22721:18) at CodeGenerator.codegen 
(C:\wamp\www\pos\node_modules\@angular\compiler-cli\src\codegen.js:30:14)
 at Function.NgTools_InternalApi_NG_2.codeGen 
(C:\wamp\www\pos\node_modules\@angular\compiler-cli\src\ngtools_api.js:
61:30)at Object.doCodegen (C:\wamp\www\pos\node_modules\@ionic\app-
scripts\dist\aot\codegen.js:6:51)at C:\wamp\www\pos\node_modules\@ionic\app-
scripts\dist\aot\aot-compiler.js:42:30

Answer 1

SOLVED

The problem was a conflict between the automatically lazy loaded components, pipes and directives that I generated using the Ionic CLI. I imported them into the main app.module.ts and they were also declared in their individual modules.

I solved the problem by removing the declarations from the app.module.ts file.