diff --git a/Gruntfile.js b/Gruntfile.js
index 413b9684..92bd0d4b 100644
--- a/Gruntfile.js
+++ b/Gruntfile.js
@@ -1,5 +1,6 @@
 module.exports = function (grunt) {
   const buildDir = "dist";
+  const schemaDir = "server/src/lib/configuration/Configuration.schema.json"
 
   grunt.initConfig({
     env: {
@@ -17,7 +18,7 @@ module.exports = function (grunt) {
       },
       "generate-config-schema": {
         cmd: "./node_modules/.bin/typescript-json-schema",
-        args: ["-o", `${buildDir}/server/src/lib/configuration/Configuration.schema.json`, "--strictNullChecks",
+        args: ["-o", schemaDir, "--strictNullChecks",
                "--required", "server/tsconfig.json", "UserConfiguration"]
       },
       "compile-client": {
@@ -86,6 +87,10 @@ module.exports = function (grunt) {
         src: '**',
         dest: `${buildDir}/server/src/public_html/js/`
       },
+      schema: {
+        src: schemaDir,
+        dest: `${buildDir}/${schemaDir}`
+      }
     },
     browserify: {
       dist: {
@@ -181,9 +186,10 @@ module.exports = function (grunt) {
   grunt.registerTask('test-int', ['run:test-int']);
 
   grunt.registerTask('copy-resources', ['copy:resources', 'copy:views', 'copy:images', 'copy:thirdparties', 'concat:css']);
+  grunt.registerTask('generate-config-schema', ['run:generate-config-schema', 'copy:schema']);
 
   grunt.registerTask('build-client', ['compile-client', 'browserify']);
-  grunt.registerTask('build-server', ['compile-server', 'copy-resources', 'run:generate-config-schema']);
+  grunt.registerTask('build-server', ['compile-server', 'copy-resources', 'generate-config-schema']);
 
   grunt.registerTask('build', ['build-client', 'build-server']);
   grunt.registerTask('build-dist', ['build', 'run:minify', 'cssmin', 'run:include-minified-script']);
diff --git a/server/src/lib/Server.ts b/server/src/lib/Server.ts
index 8f9f092a..436571fc 100644
--- a/server/src/lib/Server.ts
+++ b/server/src/lib/Server.ts
@@ -6,7 +6,7 @@ import { AppConfiguration, UserConfiguration } from "./configuration/Configurati
 import { GlobalDependencies } from "../../types/Dependencies";
 import { AuthenticationRegulator } from "./AuthenticationRegulator";
 import { UserDataStore } from "./storage/UserDataStore";
-import { ConfigurationAdapter } from "./configuration/ConfigurationAdapter";
+import { ConfigurationParser } from "./configuration/ConfigurationParser";
 import { TOTPValidator } from "./TOTPValidator";
 import { TOTPGenerator } from "./TOTPGenerator";
 import { RestApi } from "./RestApi";
@@ -110,7 +110,7 @@ export default class Server {
     const that = this;
     const app = Express();
 
-    const appConfiguration = ConfigurationAdapter.adapt(userConfiguration);
+    const appConfiguration = ConfigurationParser.parse(userConfiguration);
 
     // by default the level of logs is info
     deps.winston.level = userConfiguration.logs_level;
diff --git a/server/src/lib/configuration/Configuration.d.ts b/server/src/lib/configuration/Configuration.d.ts
index b06aecd1..802572b2 100644
--- a/server/src/lib/configuration/Configuration.d.ts
+++ b/server/src/lib/configuration/Configuration.d.ts
@@ -48,10 +48,10 @@ export type ACLGroupsRules = { [group: string]: ACLRule[]; };
 export type ACLUsersRules = { [user: string]: ACLRule[]; };
 
 export interface ACLConfiguration {
-    default_policy: ACLPolicy;
-    any: ACLDefaultRules;
-    groups: ACLGroupsRules;
-    users: ACLUsersRules;
+    default_policy?: ACLPolicy;
+    any?: ACLDefaultRules;
+    groups?: ACLGroupsRules;
+    users?: ACLUsersRules;
 }
 
 export interface SessionRedisOptions {
diff --git a/server/src/lib/configuration/Configuration.schema.json b/server/src/lib/configuration/Configuration.schema.json
index ccb76813..9fd4e923 100644
--- a/server/src/lib/configuration/Configuration.schema.json
+++ b/server/src/lib/configuration/Configuration.schema.json
@@ -85,12 +85,6 @@
                     "type": "object"
                 }
             },
-            "required": [
-                "any",
-                "default_policy",
-                "groups",
-                "users"
-            ],
             "type": "object"
         },
         "ACLPolicy": {
diff --git a/server/src/lib/configuration/ConfigurationAdapter.ts b/server/src/lib/configuration/ConfigurationParser.ts
similarity index 91%
rename from server/src/lib/configuration/ConfigurationAdapter.ts
rename to server/src/lib/configuration/ConfigurationParser.ts
index bf7365fd..32f5acf5 100644
--- a/server/src/lib/configuration/ConfigurationAdapter.ts
+++ b/server/src/lib/configuration/ConfigurationParser.ts
@@ -88,8 +88,13 @@ function adaptFromUserConfiguration(userConfiguration: UserConfiguration)
   };
 }
 
-export class ConfigurationAdapter {
-  static adapt(userConfiguration: UserConfiguration): AppConfiguration {
+export class ConfigurationParser {
+  static parse(userConfiguration: UserConfiguration): AppConfiguration {
+    const errors = Validator.isValid(userConfiguration);
+    if (errors.length > 0) {
+      errors.forEach((e: string) => { console.log(e); });
+      throw new Error("Malformed configuration. Please double-check your configuration file.");
+    }
     const appConfiguration = adaptFromUserConfiguration(userConfiguration);
 
     const ldapUrl = process.env[LDAP_URL_ENV_VARIABLE];
diff --git a/server/src/lib/configuration/Validator.ts b/server/src/lib/configuration/Validator.ts
index ce88f29a..5058d08d 100644
--- a/server/src/lib/configuration/Validator.ts
+++ b/server/src/lib/configuration/Validator.ts
@@ -1,20 +1,85 @@
 import Ajv = require("ajv");
 import Path = require("path");
+import Util = require("util");
+import {
+  UserConfiguration, StorageConfiguration,
+  NotifierConfiguration
+} from "./Configuration";
+
+function validateSchema(configuration: UserConfiguration): string[] {
+  const schema = require(Path.resolve(__dirname, "./Configuration.schema.json"));
+  const ajv = new Ajv({
+    allErrors: true,
+    missingRefs: "fail"
+  });
+  ajv.addMetaSchema(require("ajv/lib/refs/json-schema-draft-04.json"));
+  const valid = ajv.validate(schema, configuration);
+  if (!valid)
+    return ajv.errors.map(
+      (e: Ajv.ErrorObject) => { return ajv.errorsText([e]); });
+  return [];
+}
+
+function validateUnknownKeys(path: string, obj: any, knownKeys: string[]) {
+  const keysSet = new Set(Object.keys(obj));
+  const knownKeysSet = new Set(knownKeys);
+
+  const unknownKeysSet = new Set(
+    [...keysSet].filter(x => !knownKeysSet.has(x)));
+
+  if (unknownKeysSet.size > 0) {
+    const unknownKeys = Array.from(unknownKeysSet);
+    return unknownKeys.map((k: string) => { return Util.format("data.%s has unknown key '%s'", path, k); });
+  }
+  return [];
+}
+
+function validateStorage(storage: any) {
+  const ERROR = "Storage must be either 'local' or 'mongo'";
+
+  if (!storage)
+    return [];
+
+  const errors = validateUnknownKeys("storage", storage, ["local", "mongo"]);
+  if (errors.length > 0)
+    return errors;
+
+  if (storage.local && storage.mongo)
+    return [ERROR];
+
+  if (!storage.local && !storage.mongo)
+    return [ERROR];
+
+  return [];
+}
+
+function validateNotifier(notifier: NotifierConfiguration) {
+  const ERROR = "Notifier must be either 'filesystem', 'gmail' or 'smtp'";
+
+  if (!notifier)
+    return [];
+
+  const errors = validateUnknownKeys("notifier", notifier, ["filesystem", "gmail", "smtp"]);
+  if (errors.length > 0)
+    return errors;
+
+  if (notifier && notifier.filesystem && notifier.gmail && notifier.smtp)
+    return [ERROR];
+
+  if (notifier && !notifier.filesystem && !notifier.gmail && !notifier.smtp)
+    return [ERROR];
+
+  return [];
+}
 
 export class Validator {
-  static isValid(configuration: any) {
-    const schema = require(Path.resolve(__dirname, "./Configuration.schema.json"));
-    const ajv = new Ajv({
-      allErrors: true,
-      missingRefs: "fail"
-    });
-    ajv.addMetaSchema(require("ajv/lib/refs/json-schema-draft-04.json"));
-    const valid = ajv.validate(schema, configuration);
-    if (!valid) {
-      for (const i in ajv.errors) {
-        console.log(ajv.errorsText([ajv.errors[i]]));
-      }
-    }
-    return valid;
+  static isValid(configuration: any): string[] {
+    const schemaErrors = validateSchema(configuration);
+    const storageErrors = validateStorage(configuration.storage);
+    const notifierErrors = validateNotifier(configuration.notifier);
+
+    return schemaErrors
+      .concat(storageErrors)
+      .concat(notifierErrors);
   }
 }
\ No newline at end of file
diff --git a/server/test/configuration/ConfigurationAdapter.test.ts b/server/test/configuration/ConfigurationParser.test.ts
similarity index 74%
rename from server/test/configuration/ConfigurationAdapter.test.ts
rename to server/test/configuration/ConfigurationParser.test.ts
index 5a2f5299..f851dde0 100644
--- a/server/test/configuration/ConfigurationAdapter.test.ts
+++ b/server/test/configuration/ConfigurationParser.test.ts
@@ -3,10 +3,10 @@ import {
   UserConfiguration,
   LdapConfiguration, ACLConfiguration
 } from "../../src/lib/configuration/Configuration";
-import { ConfigurationAdapter } from "../../src/lib/configuration/ConfigurationAdapter";
+import { ConfigurationParser } from "../../src/lib/configuration/ConfigurationParser";
 
-describe("test config adapter", function () {
-  function build_yaml_config(): UserConfiguration {
+describe("test config parser", function () {
+  function buildYamlConfig(): UserConfiguration {
     const yaml_config: UserConfiguration = {
       port: 8080,
       ldap: {
@@ -46,50 +46,50 @@ describe("test config adapter", function () {
 
   describe("port", function () {
     it("should read the port from the yaml file", function () {
-      const yaml_config = build_yaml_config();
+      const yaml_config = buildYamlConfig();
       yaml_config.port = 7070;
-      const config = ConfigurationAdapter.adapt(yaml_config);
+      const config = ConfigurationParser.parse(yaml_config);
       Assert.equal(config.port, 7070);
     });
 
     it("should default the port to 8080 if not provided", function () {
-      const yaml_config = build_yaml_config();
+      const yaml_config = buildYamlConfig();
       delete yaml_config.port;
-      const config = ConfigurationAdapter.adapt(yaml_config);
+      const config = ConfigurationParser.parse(yaml_config);
       Assert.equal(config.port, 8080);
     });
   });
 
   it("should get the session attributes", function () {
-    const yaml_config = build_yaml_config();
+    const yaml_config = buildYamlConfig();
     yaml_config.session = {
       domain: "example.com",
       secret: "secret",
       expiration: 3600
     };
-    const config = ConfigurationAdapter.adapt(yaml_config);
+    const config = ConfigurationParser.parse(yaml_config);
     Assert.equal(config.session.domain, "example.com");
     Assert.equal(config.session.secret, "secret");
     Assert.equal(config.session.expiration, 3600);
   });
 
   it("should get the log level", function () {
-    const yaml_config = build_yaml_config();
+    const yaml_config = buildYamlConfig();
     yaml_config.logs_level = "debug";
-    const config = ConfigurationAdapter.adapt(yaml_config);
+    const config = ConfigurationParser.parse(yaml_config);
     Assert.equal(config.logs_level, "debug");
   });
 
   it("should get the notifier config", function () {
-    const yaml_config = build_yaml_config();
-    yaml_config.notifier = {
+    const userConfig = buildYamlConfig();
+    userConfig.notifier = {
       gmail: {
         username: "user",
         password: "pass",
         sender: "admin@example.com"
       }
     };
-    const config = ConfigurationAdapter.adapt(yaml_config);
+    const config = ConfigurationParser.parse(userConfig);
     Assert.deepEqual(config.notifier, {
       gmail: {
         username: "user",
@@ -101,8 +101,8 @@ describe("test config adapter", function () {
 
   describe("access_control", function() {
     it("should adapt access_control when it is already ok", function () {
-      const yaml_config = build_yaml_config();
-      yaml_config.access_control = {
+      const userConfig = buildYamlConfig();
+      userConfig.access_control = {
         default_policy: "deny",
         any: [{
           domain: "public.example.com",
@@ -116,7 +116,7 @@ describe("test config adapter", function () {
         },
         groups: {}
       };
-      const config = ConfigurationAdapter.adapt(yaml_config);
+      const config = ConfigurationParser.parse(userConfig);
       Assert.deepEqual(config.access_control, {
         default_policy: "deny",
         any: [{
@@ -135,9 +135,9 @@ describe("test config adapter", function () {
 
 
     it("should adapt access_control when it is empty", function () {
-      const yaml_config = build_yaml_config();
-      yaml_config.access_control = {} as any;
-      const config = ConfigurationAdapter.adapt(yaml_config);
+      const userConfig = buildYamlConfig();
+      userConfig.access_control = {} as any;
+      const config = ConfigurationParser.parse(userConfig);
       Assert.deepEqual(config.access_control, {
         default_policy: "deny",
         any: [],
diff --git a/server/test/configuration/LdapConfigurationAdaptation.test.ts b/server/test/configuration/LdapConfigurationAdaptation.test.ts
index 79d9ae24..59aab253 100644
--- a/server/test/configuration/LdapConfigurationAdaptation.test.ts
+++ b/server/test/configuration/LdapConfigurationAdaptation.test.ts
@@ -1,6 +1,6 @@
 import * as Assert from "assert";
 import { UserConfiguration, LdapConfiguration } from "../../src/lib/configuration/Configuration";
-import { ConfigurationAdapter } from "../../src/lib/configuration/ConfigurationAdapter";
+import { ConfigurationParser } from "../../src/lib/configuration/ConfigurationParser";
 
 describe("test ldap configuration adaptation", function () {
   function build_yaml_config(): UserConfiguration {
@@ -42,15 +42,15 @@ describe("test ldap configuration adaptation", function () {
   }
 
   it("should adapt correctly while user only specify mandatory fields", function () {
-    const yaml_config = build_yaml_config();
-    yaml_config.ldap = {
+    const userConfig = build_yaml_config();
+    userConfig.ldap = {
       url: "http://ldap",
       base_dn: "dc=example,dc=com",
       user: "admin",
       password: "password"
     };
 
-    const config = ConfigurationAdapter.adapt(yaml_config);
+    const config = ConfigurationParser.parse(userConfig);
     const expectedConfig: LdapConfiguration = {
       url: "http://ldap",
       users_dn: "dc=example,dc=com",
@@ -67,8 +67,8 @@ describe("test ldap configuration adaptation", function () {
   });
 
   it("should adapt correctly while user specify every fields", function () {
-    const yaml_config = build_yaml_config();
-    yaml_config.ldap = {
+    const userConfig = build_yaml_config();
+    userConfig.ldap = {
       url: "http://ldap-server",
       base_dn: "dc=example,dc=com",
       additional_users_dn: "ou=users",
@@ -81,7 +81,7 @@ describe("test ldap configuration adaptation", function () {
       password: "password2"
     };
 
-    const config = ConfigurationAdapter.adapt(yaml_config);
+    const config = ConfigurationParser.parse(userConfig);
     const expectedConfig: LdapConfiguration = {
       url: "http://ldap-server",
       users_dn: "ou=users,dc=example,dc=com",
diff --git a/server/test/configuration/Validator.test.ts b/server/test/configuration/Validator.test.ts
index db433f3d..69d3afca 100644
--- a/server/test/configuration/Validator.test.ts
+++ b/server/test/configuration/Validator.test.ts
@@ -1,10 +1,91 @@
 import { Validator } from "../../src/lib/configuration/Validator";
 import Assert = require("assert");
 
-describe.only("test validator", function() {
-  it("should validate a correct user configuration", function() {
-    Assert(Validator.validate({
-      ldap: {}
-    }));
+describe("test validator", function () {
+  it("should validate wrong user configurations", function () {
+    // Some examples
+    Assert.deepStrictEqual(Validator.isValid({}), [
+      "data should have required property 'ldap'",
+      "data should have required property 'notifier'",
+      "data should have required property 'regulation'",
+      "data should have required property 'session'",
+      "data should have required property 'storage'"
+    ]);
+
+    Assert.deepStrictEqual(Validator.isValid({
+      ldap: {},
+      notifier: {},
+      regulation: {},
+      session: {},
+      storage: {}
+    }), [
+        "data.ldap should have required property 'base_dn'",
+        "data.ldap should have required property 'password'",
+        "data.ldap should have required property 'url'",
+        "data.ldap should have required property 'user'",
+        "data.regulation should have required property 'ban_time'",
+        "data.regulation should have required property 'find_time'",
+        "data.regulation should have required property 'max_retries'",
+        "data.session should have required property 'secret'",
+        "Storage must be either 'local' or 'mongo'",
+        "Notifier must be either 'filesystem', 'gmail' or 'smtp'"
+      ]);
+
+    Assert.deepStrictEqual(Validator.isValid({
+      ldap: {
+        base_dn: "dc=example,dc=com",
+        password: "password",
+        url: "ldap://ldap",
+        user: "user"
+      },
+      notifier: {
+        abcd: []
+      },
+      regulation: {
+        ban_time: 120,
+        find_time: 30,
+        max_retries: 3
+      },
+      session: {
+        secret: "unsecure_secret"
+      },
+      storage: {
+        abc: {}
+      }
+    }), [
+        "data.storage has unknown key 'abc'",
+        "data.notifier has unknown key 'abcd'"
+      ]);
+  });
+
+  it("should validate correct user configurations", function () {
+    Assert.deepStrictEqual(Validator.isValid({
+      ldap: {
+        base_dn: "dc=example,dc=com",
+        password: "password",
+        url: "ldap://ldap",
+        user: "user"
+      },
+      notifier: {
+        gmail: {
+          username: "user@gmail.com",
+          password: "pass",
+          sender: "admin@example.com"
+        }
+      },
+      regulation: {
+        ban_time: 120,
+        find_time: 30,
+        max_retries: 3
+      },
+      session: {
+        secret: "unsecure_secret"
+      },
+      storage: {
+        local: {
+          path: "/var/lib/authelia"
+        }
+      }
+    }), []);
   });
 });
\ No newline at end of file