If you use visual inheritance, especially with frames, for some unknown reason the IDE decides to randomly update the .fmx file. It changes inherited to object. You may get the following error:

The solution is to close the project, open the affected .fmx file in a different text editor, and change object back to inherited. For example, from:

object ArticlesView: TArticlesView
  Size.Width = 209.000000000000000000
  Size.Height = 443.000000000000000000
  object Scroller: TVertScrollBox
    Align = Client
    Margins.Top = 8.000000000000000000
    Size.Width = 209.000000000000000000
    Size.Height = 435.000000000000000000
    Size.PlatformDefault = False
    TabOrder = 0
    Viewport.Width = 209.000000000000000000
    Viewport.Height = 435.000000000000000000
  end
end

to:

inherited ArticlesView: TArticlesView
  Size.Width = 209.000000000000000000
  Size.Height = 443.000000000000000000
  object Scroller: TVertScrollBox
    Align = Client
    Margins.Top = 8.000000000000000000
    Size.Width = 209.000000000000000000
    Size.Height = 435.000000000000000000
    Size.PlatformDefault = False
    TabOrder = 0
    Viewport.Width = 209.000000000000000000
    Viewport.Height = 435.000000000000000000
  end
end

I hope this tip helps.