How to: Enable Diagnostics

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For the latest documentation on Visual Studio 2017, see Visual Studio 2017 Documentation.

You can find and fix errors that occur in the code that you write by debugging your application. There are, however, errors that can occur outside the code that you write. For example, there are many issues that could prevent your application from communicating with a server. To find and fix these types of errors, LightSwitch provides diagnostic capabilities both at design time and for a deployed application. Diagnostics is accomplished by enabling tracing on the client or on the server.

Important

When tracing is enabled for a LightSwitch application, trace information might appear on any browser that makes a request for the application from the server. Tracing is a security threat because it displays sensitive information, such as the values of server variables. Disable tracing for the application before you publish it to a production server.

To enable client tracing at design time

  1. In Solution Explorer, open the shortcut menu for the My Project node and choose Open.

    Note

    For HTML Client applications, skip to step 3.

  2. In the Application Designer, choose the Edit DesktopClient properties link, choose the Client Type tab, and then choose the Web option.

  3. On the menu bar, choose View, Output to display the Output window.

  4. On the menu bar, choose Debug,Start Debugging.

  5. In the address bar of the browser, add client tracing arguments to the end of the URL as follows:

    • To display an error-level trace, enter LC=Microsoft.LightSwitch,E.

    • To display a warning-level trace, enter LC=Microsoft.LightSwitch,W.

    • To display an information-level trace, enter LC=Microsoft.LightSwitch,I.

    • To display a verbose trace, enter LC=Microsoft.LightSwitch,V.

    For example, following is the full URL for a verbose trace for an application named myapp.

    https://myapp/default.htm?LC=Microsoft.LightSwitch,V

    The application restarts and trace messages appear in the Output window.

To enable server tracing at design time

  1. In Solution Explorer, expand the Server node, and the open the shortcut menu for the Web.config node and choose Open..

  2. In the <appSettings> section, find the line <add key=”Microsoft.LightSwitch.Trace.Enabled” value=”false” /> and change false to true.

  3. Close the Web.config file, and when you are prompted to save changes choose Yes.

  4. In Solution Explorer, opem the shortcut menu for the My Project node and choose Open.

  5. In the Application Designer, choose the Client Type tab, and then choose the Web option..

  6. Run the application. The application will open in your default Web browser.

  7. Copy the first part of the URL from the Address Bar of the browser. It should resemble https://localhost:12345, but with a different numeric value.

  8. Open a new Web browser window or tab, and in the Address Bar paste the URL that you copied, and then enter /Trace.axd. It should resemble https://localhost:12345/Trace.axd.

    This will display trace information for server operations.

To enable client tracing for a deployed 3-tier Web application

  1. Open a Web browser and navigate to the URL for the application.

  2. In the address bar of the browser, add client tracing arguments to the end of the URL as follows:

    • To display an error-level trace, enter LC=Microsoft.LightSwitch,E.

    • To display a warning-level trace, enter LC=Microsoft.LightSwitch,W.

    • To display an information-level trace, enter LC=Microsoft.LightSwitch,I.

    • To display a verbose trace, enter LC=Microsoft.LightSwitch,V.

    For example, following is the full URL for a verbose trace for an application named myapp.

    https://myapp/default.htm?LC=Microsoft.LightSwitch,V

  3. View the trace messages in a debug viewer. Any debug viewer that can listen to debug output messages can be used to view LightSwitch trace messages.