Oh und what solution do they propose ?
Not doing another full installation with new domain creation or ? Then direct upgrading is not an option :-(
I haven't tried it, but this is their workaround
1) delete the reportsInstance using WLST command
2) Then run UA -readiness check and it succeeds
the advice from the reports team in the SR that I raised was to delete the reportstoolsinstance, perform the upgrade and then install the reportstoolsinstance again
what concerns me the most is that no-one at Oracle has tested the upgrade process with a reportstoolinstance in place, or if they did, they knowingly let it go out the door with it not working and didn't tell us