Thanks for your issue! This is not related to this repo. The reason: The builder API has changed with Angular 8. A PR for @ionic/angular-toolkit is already available but not published so far (see https://github.com/ionic-team/angular-toolkit/pull/132 )

At the moment Angular 8 is not supported.

If you cannot wait (like me 😉), just replace @ionic/angular-toolkit inside angular.json with paulstelzer-ionic-angular-toolkit and run npm i paulstelzer-ionic-angular-toolkit. This is the build of the mentioned branch. After @ionic/angular-toolkit got the new release you can use this again

Seeing this too after upgrading to Angular 8 and trying to run an ionic cordova build.

Could not find the implementation for builder @ionic/angular-toolkit:cordova-build at WorkspaceNodeModulesArchitectHost.resolveBuilder (/node_modules/@angular-devkit/architect/node/node-modules-architect-host.js:49:19) at RunCommand.runSingleTarget (/node_modules/@angular/cli/models/architect-command.js:176:55)

Hey folks! Angular-toolkit 2.0 has been released, please move off of the unofficial version.

Thanks for your issue! This is not related to this repo. The reason: The builder API has changed with Angular 8. A PR for @ionic/angular-toolkit is already available but not published so far (see ionic-team/angular-toolkit#132 )

At the moment Angular 8 is not supported.

If you cannot wait (like me 😉), just replace @ionic/angular-toolkit inside angular.json with paulstelzer-ionic-angular-toolkit and run npm i paulstelzer-ionic-angular-toolkit. This is the build of the mentioned branch. After @ionic/angular-toolkit got the new release you can use this again

Saved me on this one 😉

I have the same problem after upgrading to Angular 8

I don’t know why but I have the same issue with recommended @ionic/angular-toolkit version 2.

$ npm "install" "-g" "cordova@latest"
$ npm "install" "-g" "ionic@latest"

cordova version: 9.0.0
ionic version: 5.2.3

$ ionic "cordova" "build" "--release" "--device" "ios" "--buildConfig" "/var/folders/6q/wgy6jtp12w5gzgm9lzcglpqw0000gn/T/__bitrise-cordova-build-config__380555088/build.json" "--" "--buildFlag=-UseModernBuildSystem=0"
> cordova platform add ios --save
Using cordova-fetch for cordova-ios@^5.0.0
Adding ios project...
Creating Cordova project for the iOS platform:
	Path: platforms/ios
	Package: org.example
	Name: Example
iOS project created with cordova-ios@5.0.1
Plugin 'cordova-plugin-whitelist' found in config.xml... Migrating it to package.json
Plugin 'cordova-plugin-statusbar' found in config.xml... Migrating it to package.json
Plugin 'cordova-plugin-device' found in config.xml... Migrating it to package.json
Plugin 'cordova-plugin-splashscreen' found in config.xml... Migrating it to package.json
Plugin 'cordova-plugin-ionic-webview' found in config.xml... Migrating it to package.json
Plugin 'cordova-plugin-mauron85-background-geolocation' found in config.xml... Migrating it to package.json
Plugin 'ionic-plugin-deeplinks' found in config.xml... Migrating it to package.json
Plugin 'cordova-plugin-geolocation' found in config.xml... Migrating it to package.json
Plugin 'cordova-plugin-telerik-imagepicker' found in config.xml... Migrating it to package.json
Plugin 'onesignal-cordova-plugin' found in config.xml... Migrating it to package.json
Plugin 'cordova-plugin-camera' found in config.xml... Migrating it to package.json
Plugin 'cordova-plugin-facebook4' found in config.xml... Migrating it to package.json
Discovered saved plugin "cordova-plugin-file". Adding it to the project
Installing "cordova-plugin-file" for ios
Adding cordova-plugin-file to package.json
Discovered saved plugin "cordova-plugin-ionic-keyboard". Adding it to the project
Installing "cordova-plugin-ionic-keyboard" for ios
Adding cordova-plugin-ionic-keyboard to package.json
Discovered saved plugin "cordova-plugin-whitelist". Adding it to the project
Installing "cordova-plugin-whitelist" for ios
Adding cordova-plugin-whitelist to package.json
Discovered saved plugin "cordova-plugin-statusbar". Adding it to the project
Installing "cordova-plugin-statusbar" for ios
Adding cordova-plugin-statusbar to package.json
Discovered saved plugin "cordova-plugin-device". Adding it to the project
Installing "cordova-plugin-device" for ios
Adding cordova-plugin-device to package.json
Discovered saved plugin "cordova-plugin-splashscreen". Adding it to the project
Installing "cordova-plugin-splashscreen" for ios
Adding cordova-plugin-splashscreen to package.json
Discovered saved plugin "cordova-plugin-ionic-webview". Adding it to the project
Installing "cordova-plugin-ionic-webview" for ios
Adding cordova-plugin-ionic-webview to package.json
Discovered saved plugin "cordova-plugin-mauron85-background-geolocation". Adding it to the project
Installing "cordova-plugin-mauron85-background-geolocation" for ios
Adding cordova-plugin-mauron85-background-geolocation to package.json
Discovered saved plugin "ionic-plugin-deeplinks". Adding it to the project
Installing "ionic-plugin-deeplinks" for ios
Adding ionic-plugin-deeplinks to package.json
Discovered saved plugin "cordova-plugin-geolocation". Adding it to the project
Installing "cordova-plugin-geolocation" for ios
Adding cordova-plugin-geolocation to package.json
Discovered saved plugin "cordova-plugin-telerik-imagepicker". Adding it to the project
Installing "cordova-plugin-telerik-imagepicker" for ios
Adding cordova-plugin-telerik-imagepicker to package.json
Discovered saved plugin "onesignal-cordova-plugin". Adding it to the project
Installing "onesignal-cordova-plugin" for ios
"framework" tag with type "podspec" is deprecated and will be removed. Please use the "podspec" tag.
Running command: pod install --verbose
     Cloning into '/var/folders/6q/wgy6jtp12w5gzgm9lzcglpqw0000gn/T/d20190801-2536-mt1bq'...
     Note: checking out '9271672bd77326df1063393451948b456ed9cbea'.
     
     You are in 'detached HEAD' state. You can look around, make experimental
     changes and commit them, and you can discard any commits you make in this
     state without impacting any branches by performing another checkout.
     
     If you want to create a new branch to retain commits you create, you may
     do so (now or later) by using -b with the checkout command again. Example:
     
       git checkout -b <new-branch-name>
     
Adding onesignal-cordova-plugin to package.json
Discovered saved plugin "cordova-plugin-camera". Adding it to the project
Installing "cordova-plugin-camera" for ios
Adding cordova-plugin-camera to package.json
Discovered saved plugin "cordova-plugin-facebook4". Adding it to the project
Installing "cordova-plugin-facebook4" for ios
Adding cordova-plugin-facebook4 to package.json
> ng run app:ionic-cordova-build --platform=ios
An unhandled exception occurred: Could not find the implementation for builder @ionic/ng-toolkit:cordova-build
See "/private/var/folders/6q/wgy6jtp12w5gzgm9lzcglpqw0000gn/T/ng-9GGUs2/angular-errors.log" for further details.
[ERROR] An error occurred while running subprocess ng.
        
        ng run app:ionic-cordova-build --platform=ios exited with exit code 127.
        
        Re-running this command with the --verbose flag may provide more information.
command failed, error: exit status 127

An unhandled exception occurred: Could not find the implementation for builder @ionic/ng-toolkit:cordova-build

cordova version: 9.0.0 ionic version: 5.2.3

"@ionic/angular-toolkit": "^2.0.0"

As I wrote above: just replace @ionic/angular-toolkit inside angular.json with paulstelzer-ionic-angular-toolkit and run npm i paulstelzer-ionic-angular-toolkit.