RQP-DEF-0120 Database connection is dropped (Cognos 10.2.1 FP5)

[RubenvdLinden]

I'm currently testing Cognos 10.2.1 FP5 (production is still running Cognos 10.1.1 FP2) and all the reports seem to work just fine, except reports on a really old Oracle 9.2.0.4 database server.
Looking at the Cognos 10.2.1 supported environments report I suspect Oracle 9.2.0.4 is no longer supported, so we performed a test migration to Oracle 11.2.0.4.
I'm testing the impact of this database update on both our Cognos 10.1.1 FP2 and Cognos 10.2.1 FP5.

One of the reports fails on both environments with the error "UDA-EE-0011 A freeform number is invalid.UDA-SQL-0460 A general exception has occurred during local processing."
I'm still looking into that, but I noticed a difference in behaviour between Cognos 10.1.1 FP2 and Cognos 10.2.1 FP5.
I can re-run the report immediately (with or without adjustment) in Cognos 10.1.1 FP2. However, if I immediately try to re-run the report in Cognos 10.2.1 FP5 it throws an error:

RQP-DEF-0120 Database connection is dropped.

If I logoff and logon again, I can re-run the report again. However, I have no problems running other reports on the same database even directly after encountering the "Database dropped" problem.