Getting an error during start of the project

[PauloA78]

Getting this error
System.ArgumentException: 'Assembly 'C:\Users\paulo.almeida\Downloads\Calendar\Winforms-Calendar-master\WindowsFormsCalendar\obj\Debug\WindowsFormsCalendar.dll' doesn't contain any UserControl types.'

And
Symbol loading for optimized module UserControlTestContainer.exe was skipped because Just My Code is enabled

Any Idea ?

Thx