You can open an existing dashboard that you created with the classic dashboard editor and transfer it to the new editor.
Procedure
The selected dashboard opens in the new dashboard editor.
The dashboard is saved as a copy with the new name.
When you save the dashboard for the first time, a copy of the dashboard is created. You can now edit the dashboard in the new dashboard editor. The original dashboard remains unchanged.
Tip
You can replace the original dashboard with the content of the current (new) dashboard. Click Save ->
Overwrite -> Select a dashboard -> Click Overwrite. The identifier (GUID), permissions, and bookmarks of the selected dashboard are preserved.