Fixing steps:

1. Stop the dbconsole

2. Relink the agent component manually using this procedure :
2.1 Make a copy of $ORACLE_HOME/sysman/lib/env_sysman.mk (as backup)
2.2 Edit the script $ORACLE_HOME/sysman/lib/env_sysman.mk adding $(LIBNMO) as follows:
- search the link line looking for string "MK_EMDW_LIBNMEMSO_SHLIB"
- replace the line
$(LIBNMEM) $(LIBNMER)
with
$(LIBNMEM) $(LIBNMER) $(LIBNMO)
2.3 Perform the following relink:
% cd $ORACLE_HOME/sysman/lib
% make -f ins_sysman.mk agent

[@more@]
This will not affect the other database components as only the agent is being relinked.