It’s a very strange mistake.
We have a Spark 2.8.3 client and an Openfire 4.4.1 server in connection with Kerberos.
Our Spark customers log in with SSO for “normal users” without problems, but in case the user has local administrator privileges in the machine, Spark startup fails.
The solution is to mark Spark.exe as “Run this program as administrator…” if you want a successful startup.
iirc, this is more of a UAC issue. Windows is protecting the token for administators. options are a little limited. you can run as administrator, tweak uac, or create a uac exception (although I don’t recall how to do this).