Unable to open an ICS file in Notes 8.5.2 and 8.5.3.
Opening the ICS file gives the error:
"Notes cannot process your file. The URL is not associated with a valid iCalendar feed."
The ICS filename had a Trademark (TM) in the file name.
Seen in 8.5.2 and 8.5.3
Resolving the problem
ICS file opens properly in 8.5.1. Removing the Trademark (TM) by renaming the file resolves the issue in 8.5.2 and 8.5.3.