Hello everyone. The title is long.
This time, we'll be talking about how the "Switch to Classic" button in the app designer has been hidden.

What is an app designer?

When Microsoft products and services make significant changes to their UI, they refer to the old UI as "Classic XX" and the new UI as "Modern XX." The app designer used to customize model-driven apps in Dynamics 365 and Power Apps released a new UI, "Modern Designer," in the spring of 2021.

Let's compare the major changes to the UI by opening the form for the same business partner.

[Example of Classic Designer (client company form editing screen)]

[Modern Designer example (Customer table form editing screen)]

For those who have only ever seen modern designers, you can think of the older UI as the classic designer. Modern has the advantage of being easy to use because the preview screen is closer to the design of the actual app screen. Classic has the advantage of allowing for more efficient customization work, and personally, I use them interchangeably: modern if ease of understanding is the priority, and classic if work efficiency is the priority .

Classic Designer Deprecated

Microsoft recommends the Modern Designer, and the editing screen will be displayed in the Modern Designer.
However, the "Switch to Classic" button was displayed, and it was possible to switch.

However, recently (around November 2023), the "Switch to Classic" option has been hidden by default.
The classic App, Form, and View designer has been deprecated

If you actually look at the screen, even if you select "..." on the command bar, the following message will be displayed and you will not be able to switch.

How to display the Switch to Classic button

At the time of writing this blog, a workaround is available. To implement this method, a user with a security role that can change Dataverse settings, such as "System Administrator," must operate it. If you are unsure, please contact your administrator.

1. Open the Power Platform admin center (https://admin.powerplatform.microsoft.com).
2. Select [Environment] > [Target environment] > [Settings] > [v] Product > [Behavior].
3. Change "Show 'Switch to Classic' button in Power Apps" to "On" and select "Save."
   
4. In the app designer, select "..." on the command bar to display the "Switch to Classic" button.
   

Summary

Since it has been clearly stated that Classic Designer is deprecated, it is possible that this setting will also be abolished depending on user reaction.
However, if you need to customize efficiently, we recommend that you try out the Classic Designer.