NAV Development Preview – August Update

The August update for Developer Preview is now live! With this update, we announce the following changes:

  • In this update, based on your requests, you can work with three different country versions of the application database. This is provided through hosting them on the Dev Preview VM; each with their own NST. The services that are available and the names that you should use in serverInstance setting in launch.json file are the following: “US”, “GB”, and “CA”. The US, GB, and CA versions correspond to the Dynamics 365 for Financials user experience and application database.
    If you need to code against W1, you will have to enable the developer service endpoint in the Administration Console for the NAV serverInstance and use “NAV” in the serverInstance setting in launch.json file. Note, that the NAV serverInstance is using UserPassword authentication and the other instances are using Windows Authentication.
  • We’ve added an early preview of the new debugging experience to the VS Code extension.
    The semantics of pressing F5 in the VS Code extension has changed – now F5 will start a debugging sessionTo start the client without debugging, use Ctrl+F5.
    To hit the breakpoints in the debugger, you just trigger the relevant actions in the web interface.


    • No support yet of watch or conditional breakpoints
    • No breakpoints can be set in “external code” such as base application objects, though you can step through them
    • Not all AL types yet show helpful debugging
    • Each file must contain only one application object for the breakpoints to be evaluated correctly
    • The debugger launches a new client instance each time you press F5. If you close the debugging session, and then start a new session, this new session will rely on a new client instance. We recommend that you close the Web client instances when you close a debugging session.  
    • If you stop at a breakpoint and then walk the call stack, you risk seeing duplicate stack traces. This is an issue in VS Code, and we are working with them to get this resolved.
    • And finally, using the debugger with the online sandbox signup and AAD authentication method is not yet supported.
  • We continue to add replacements for highly requested .NET types. This update adds a new AL type, TextBuilder, that wraps the most commonly used functionality of the System.StringBuilder type in the .NET Framework.
  • We’ve also enriched the built-in Text data type with a bunch of new functions – for a full list, see
  • Our VS Code extension comes with more new capabilities again this time:
    • The popular “Go To Definition” for dependencies gives you a generated version of the application objects, such as which fields a table has, and the datatypes of the fields. Simply place your cursor on the type and press F12.
      Note: Properties and attributes are not yet supported.
    • New authentication methods are now available:
      The property windowsAuthentication in the launch.json file is deprecated, although it will still work.
      Instead, set the new authentication property to the following values:

      • Windows
      • UserPassword
      • AAD
        Make sure you use the new property going forward.

Finally, a reminder to get the latest docs for the preview by typing We’re continuously working on updating and improving the library.

Let us know how you like working with these additions and keep submitting suggestions and bugs. You can see all the filed bugs on our GitHub issues list ( To get an updated image you can see the steps for getting it in the original blog post or jump directly to the Azure Gallery signup at

For a list of our previous blog posts, see the links at the end of this post.


Our earlier blog posts:

NAV Development Tools Preview – July Update

NAV Development Tools Preview – June Update

NAV Development Tools Preview – April Update

NAV Development Tools Preview – March Update

NAV Development Tools Preview – February Update

NAV Development Tools Preview – January Update

Announcing the Preview of Modern Development Tools for Dynamics NAV