Error: $injector:unpr

Unknown Provider

This error results from the $injector being unable to resolve a required dependency. To fix this, make sure the dependency is defined and spelled correctly. For example:

angular.module('myApp', [])
.controller('MyController', ['myService', function (myService) {
  // Do something with myService
}]);

The above code will fail with $injector:unpr if myService is not defined.

Making sure each dependency is defined will fix the problem, as noted below.

angular.module('myApp', [])
.service('myService', function () { /* ... */ })
.controller('MyController', ['myService', function (myService) {
  // Do something with myService
}]);

An unknown provider error can also be caused by accidentally redefining a module using the angular.module API, as shown in the following example.

angular.module('myModule', [])
  .service('myCoolService', function () { /* ... */ });

angular.module('myModule', [])
  // myModule has already been created! This is not what you want!
  .directive('myDirective', ['myCoolService', function (myCoolService) {
    // This directive definition throws unknown provider, because myCoolService
    // has been destroyed.
  }]);

To fix this problem, make sure you only define each module with the angular.module(name, [requires]) syntax once across your entire project. Retrieve it for subsequent use with angular.module(name). The fixed example is shown below.

angular.module('myModule', [])
  .service('myCoolService', function () { /* ... */ });

angular.module('myModule')
  .directive('myDirective', ['myCoolService', function (myCoolService) {
    // This directive definition does not throw unknown provider.
  }]);

Attempting to inject one controller into another will also throw an Unknown provider error:

angular.module('myModule', [])
.controller('MyFirstController', function() { /* ... */ })
.controller('MySecondController', ['MyFirstController', function(MyFirstController) {
  // This controller throws an unknown provider error because
  // MyFirstController cannot be injected.
}]);

Use the $controller service if you want to instantiate controllers yourself.

Attempting to inject a scope object into anything that's not a controller or a directive, for example a service, will also throw an Unknown provider: $scopeProvider <- $scope error. This might happen if one mistakenly registers a controller as a service, ex.:

angular.module('myModule', [])
.service('MyController', ['$scope', function($scope) {
  // This controller throws an unknown provider error because
  // a scope object cannot be injected into a service.
}]);

If you encounter this error only with minified code, consider using ngStrictDi (see ngApp) to provoke the error with the non-minified source.