troubleshoot .net installation failure

Author: mumian

articles/azure-resource-manager/bicep/install.md

@@ -2,7 +2,7 @@
 title: Set up Bicep development and deployment environments
 description: How to configure Bicep development and deployment environments
 ms.topic: conceptual
-ms.date: 10/01/2021
+ms.date: 10/20/2021
 ms.custom: devx-track-azurepowershell, devx-track-azurecli
 ---
 
@@ -27,6 +27,47 @@ To verify you've installed the extension, open any file with the `.bicep` file e
 
 :::image type="content" source="./media/install/language-mode.png" alt-text="Bicep language mode":::
 
+### Troubleshoot
+
+When install the Bicep extension for Visual Studio Code, you may run into the following error messages:
+
+```error
+Failed to install .NET runtime v5.0
+```
+
+or
+
+```error
+Failed to download .NET 5.0.x ....... Error!
+```
+
+To solve the problem, you can manually install .NET from the [.NET website](https://aka.ms/dotnet-core-download), and then configure Visual Studio Code to reuse an existing installation of .NET. by using the following settings:
+
+**Windows**
+
+```json
+"dotnetAcquisitionExtension.existingDotnetPath": [
+  {
+    "extensionId": "msazurermtools.azurerm-vscode-tools",
+    "path": "C:\\Program Files\\dotnet\\dotnet.exe"
+  }
+]
+
+```
+
+**Mac**
+
+```json
+"dotnetAcquisitionExtension.existingDotnetPath": [
+  {
+    "extensionId": "msazurermtools.azurerm-vscode-tools",
+    "path": "/usr/local/share/dotnet/dotnet"
+  }
+]
+```
+
+See [User and Workspace Settings](https://code.visualstudio.com/docs/getstarted/settings) for configuring Visual Studio Code settings.
+
 ## Deployment environment
 
 After setting up your development environment, you need to install the tools for your deployment environment. To set up a local deployment environment, install the Bicep CLI with [Azure CLI](#azure-cli) or [Azure PowerShell](#azure-powershell). Those steps are shown in the next sections.