Hi @stevenr,
the thing about kopano not starting after the upgrade already came up in Fehler nach Upgrade 4.2: Kopano startet nicht mehr, but up until now i was not able to reproduce this locally so its still unclear what could be wrong (although the last reply with the connection of not waiting long enough for mysql sounds plausible).
for the files plugin i only know about Kopano WebApp File Integration Error in relation to Univention.