Renaming of measures and/or BTs fails.
A popup message appears when trying to rename a business transaction or a measure.
Also, a similar NPE is logged into the server log:
SEVERE [BaseServerAccessController] Failed to access server: com.dynatrace.diagnostics.server.BaseServerAccessController$1 handle:85
The issue was introduced in AppMon 6.3.4, and affects AppMon 6.3.5, 6.3.6 as well.