Many users has experienced the problem when using custom property Data Type: File, it does not work at all.
In order to fix this, you can do the following:
1. Login as Host account
2. Navigate to Host >> Module Definitions
3. Click the Edit pencil at the left side of Events Calendar module. (if you do not see the edit pencil, try change it to Edit view from the top left corner).
4. Then you will find a list of controls under Events Calendar module.
5. Click on the Edit pencil beside the Edit control (Edit Events Calendar)
6. And uncheck the "Allow Partial Rendering", and then click Update.
7. Click on the Edit pencil which is having an empty control. (DesktopModules/EventsCalendar/View.ascx
8. And uncheck the "Allow Partial Rendering", and then click Update.
After that, your custom properties with File data type should work.
This is due a bug from Microsoft ASP.NET Ajax, which does not support file upload. Microsoft does not have a solution on this, neither we do. :( read more...