diff --git a/docs/configuration/appx.md b/docs/configuration/appx.md
index b9045b4e49e..007792f84a2 100644
--- a/docs/configuration/appx.md
+++ b/docs/configuration/appx.md
@@ -4,7 +4,7 @@ All options are optional. All required for AppX configuration is inferred and co
 
 <!-- do not edit. start of generated block -->
 <ul>
-<li><code id="AppXOptions-applicationId">applicationId</code> String - The application id. Defaults to <code>identityName</code>.</li>
+<li><code id="AppXOptions-applicationId">applicationId</code> String - The application id. Defaults to <code>identityName</code>. This string contains alpha-numeric fields separated by periods. Each field must begin with an ASCII alphabetic character.</li>
 <li><code id="AppXOptions-backgroundColor">backgroundColor</code> = <code>#464646</code> String | “undefined” - The background color of the app tile. See <a href="https://msdn.microsoft.com/en-us/library/windows/apps/br211471.aspx">Visual Elements</a>.</li>
 <li><code id="AppXOptions-displayName">displayName</code> String | “undefined” - A friendly name that can be displayed to users. Corresponds to <a href="https://msdn.microsoft.com/en-us/library/windows/apps/br211432.aspx">Properties.DisplayName</a>. Defaults to the application product name.</li>
 <li><code id="AppXOptions-identityName">identityName</code> String | “undefined” - The name. Corresponds to <a href="https://msdn.microsoft.com/en-us/library/windows/apps/br211441.aspx">Identity.Name</a>. Defaults to the <a href="/configuration/configuration#Metadata-name">application name</a>.</li>
diff --git a/packages/app-builder-lib/scheme.json b/packages/app-builder-lib/scheme.json
index d446af0a188..b9bfcc865b7 100644
--- a/packages/app-builder-lib/scheme.json
+++ b/packages/app-builder-lib/scheme.json
@@ -153,7 +153,7 @@
           "type": "boolean"
         },
         "applicationId": {
-          "description": "The application id. Defaults to `identityName`. This string contains alpha-numeric fields separated by periods. Each field must begin with an ASCII alphabetic character",
+          "description": "The application id. Defaults to `identityName`. This string contains alpha-numeric fields separated by periods. Each field must begin with an ASCII alphabetic character.",
           "type": "string"
         },
         "artifactName": {
diff --git a/packages/app-builder-lib/src/options/AppXOptions.ts b/packages/app-builder-lib/src/options/AppXOptions.ts
index c8a657903a3..d5e2a3e9932 100644
--- a/packages/app-builder-lib/src/options/AppXOptions.ts
+++ b/packages/app-builder-lib/src/options/AppXOptions.ts
@@ -2,7 +2,7 @@ import { TargetSpecificOptions } from "../core"
 
 export interface AppXOptions extends TargetSpecificOptions {
   /**
-   * The application id. Defaults to `identityName` This string contains alpha-numeric fields separated by periods. Each field must begin with an ASCII alphabetic character.
+   * The application id. Defaults to `identityName`. This string contains alpha-numeric fields separated by periods. Each field must begin with an ASCII alphabetic character.
    */
   readonly applicationId?: string
 
diff --git a/packages/app-builder-lib/src/targets/AppxTarget.ts b/packages/app-builder-lib/src/targets/AppxTarget.ts
index de0700018d1..c32928c5a0e 100644
--- a/packages/app-builder-lib/src/targets/AppxTarget.ts
+++ b/packages/app-builder-lib/src/targets/AppxTarget.ts
@@ -226,11 +226,11 @@ export default class AppXTarget extends Target {
         case "applicationId": {
           const validCharactersRegex = /^([A-Za-z][A-Za-z0-9]*)(\.[A-Za-z][A-Za-z0-9]*)*$/
           const identitynumber = parseInt(options.identityName as string, 10) || NaN
-		  let result:string
+          let result: string
           if (!isNaN(identitynumber) && options.identityName !== null && options.identityName !== undefined) {
             if (options.identityName[0] === "0") {
               log.warn(`Remove the 0${identitynumber}`)
-              result = options.identityName.replace("0"+identitynumber.toString(), "")
+              result = options.identityName.replace("0" + identitynumber.toString(), "")
             } else {
               log.warn(`Remove the ${identitynumber}`)
               result = options.identityName.replace(identitynumber.toString(), "")
@@ -246,7 +246,7 @@ export default class AppXTarget extends Target {
             const message = `AppX Application.Id can not be consists of alpha-numeric and period"`
             throw new InvalidConfigurationError(message)
           } else if (restrictedApplicationIdValues.includes(result.toUpperCase())) {
-            const message = `AppX Application.Id can not be some values`
+            const message = `AppX identityName.Id can not include restricted values: ${JSON.stringify(restrictedApplicationIdValues)}`
             throw new InvalidConfigurationError(message)
           } else if (result == null && options.applicationId == null) {
             const message = `Please set appx.applicationId (or correct appx.identityName or name)`