Problem after Updating in Lovelace

Hello after updating to 0.81.0.dev0,
i get following error in my LovelaceUI:

          #  color_type: blank-card
      - id: 642aec22cdbf46b7bd512a26ad736afd  # Automatically created id
        type: vertical-stack
          - type: custom:weather-card
            entity_weather: weather.yweather
            entity_sun: sun.sun
          - type: iframe

what did i do wrong, it was perfect before the update, i think?
I use more vertical stacks in my build and any other is running smoothly,
thx in Advance