ORA-20006: Number of RAC active instances and opatch jobs configured are not same

Following error could be observed when running the "Loading Modified SQL Files into the Database" section under the "Patch Post-Installation Instructions" during a PSU apply. In this case the system was a 2 node 12c RAC. and was installing the 12.1.0.1.3 Patch Set Update.

[oracle@rhel6m1 OPatch]$ ./datapatch -verbose
SQL Patching tool version 12.1.0.1.0 on Wed May  7 17:04:06 2014
Copyright (c) 2014, Oracle.  All rights reserved.

Connecting to database...OK
Determining current state...
Currently installed SQL Patches: 17552800
DBD::Oracle::st execute failed: ORA-20006: Number of RAC active instances and opatch jobs configured are not same
ORA-06512: at "SYS.DBMS_QOPATCH", line 1007
ORA-06512: at line 4 (DBD ERROR: OCIStmtExecute) [for Statement "DECLARE
       x XMLType;
     BEGIN
       x := dbms_qopatch.get_pending_activity;
       ? := x.getStringVal();
     END;" with ParamValues: :p1=undef] at /opt/app/oracle/product/12.1.0/dbhome_1/sqlpatch/sqlpatch.pm line 1227.

Patch apply was carried out in a rolling fashion. Node 1 patched and brought up and then node 2 patched. While the node 2 patch apply is going on the post patch installation steps are carried out on the already started node (as these steps only need to be carried out on a single instance).
From the error above it seems this method (which worked on 11g) is no longer possible with the new datapatch utility. Metalink notes 1530108.1 and 1599479.1 list "ORA-20006: Number of RAC active instances and opatch jobs configured are not same" as "error which might be encountered during execution of Queryable Patch Inventory"



Solution provided on the above notes for this issue is to obtain support from Oracle!
Other workaround is wait until all the instances to start and then apply the post patch steps which doesn't result in an error.

[oracle@rhel6m1 OPatch]$ ./datapatch -verbose
SQL Patching tool version 12.1.0.1.0 on Wed May  7 17:15:00 2014
Copyright (c) 2014, Oracle.  All rights reserved.

Connecting to database...OK
Determining current state...
Currently installed SQL Patches: 17552800
Currently installed C Patches: 18031528
Adding patches to installation queue and performing prereq checks...
Installation queue:
  Nothing to roll back
  The following patches will be applied: 18031528
  Bundle patch 17552800 is included in bundle patch 18031528, so it does not need to be rolled back
Installing patches...

Useful metalink notes
Oracle Database 12.1 : FAQ on Queryable Patch Inventory [ID 1530108.1]
Datapatch errors at "SYS.DBMS_QOPATCH" [ID 1599479.1]