I used many plugins in my Ionic 2 project. All things works fine before. But after launching ionic state reset --plugins, some objects cannot be found any more.
I've used Beacon Plugin in my project.
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What it doesn't work is
Cannot read property 'Delegate' of undefined in var delegate = new this.locationManager.Delegate();
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The most weird thing is that ionic serve works (Browser), but ionic run android (Device) doesn't.
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After ionic platform rm android and ionic platform add android, still doesn't works.
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Doesn't work even I reinstall the Cordova.
The command
ionic state reset --plugins
removes everything and then bring back what you have specified in the package.json file. Is the Beacon Plugin reference in your project's package.json file? If not, you will have to run
ionic plugin add https://github.com/petermetz/cordova-plugin-ibeacon.git
to add it again. Once everything is working again, you can run the following command in order to save current plugins / platforms to the package.json:
ionic state save
And then, if you need to quickly load in plugins and platforms, you can simply do:
ionic state restore
And Ionic will add in the appropriate plugins and platforms.
来源：https://stackoverflow.com/questions/37679723/after-reseting-plugins-ionic-2-program-doesnt-work