Error NOTES 8.5.1 : Type mismatch on external name CSCALENDARENTRY

when you add a new activity in your calendar will have the error that "Type mismatch on external name CSCALENDARENTRY"

Resolve

1. Open your calendar, and then go to File menu, Application, Replace Design.

2. In the Replace Design dialog box, Select "Mail (R8.5) or your Template" and then click Replace.

3. wait until complete .

4. Restart Lotus Notes.