Notes / Domino by Ulrich Krause
HCL Notes Client – “Invalid RTF Data On The Clipboard” 
By Ulrich Krause | 12/3/22 11:30 AM | Infrastructure - Notes / Domino | Added by Oliver Busse
The issue applies to HCL Notes 12.0.1 standard and basic as well as HCL Notes 12.0.2 32/64Bit standard and basic.
When you try to change your signature in the Calendar Profile, you get the error message