Ever ran into an ORA-19755 with RMAN?

Ever ran into an ORA-19755 with RMAN duplicate from target? When your source database uses block change tracking?

Try patch 11744544; it fixes the bug which could might cause block change tracking recreation fail in combination with OMF newnames.

A workaround would be to disable change tracking before duplicating.

EM agent; ERROR-400 Data will be rejected for upload, bla bla

Darn, I had it also, the agent in GRID control in not uploading to the OMS and there is just too much to upload. One can change em.loader.maxDirectLoadFileSz but the following can be done to (you will lose some info but hey..)

Now fix it:

cd $AGENT_HOME/sysman/emd
rm lastupld.xml agntstmp.txt
cd $AGENT_HOME/sysman/emd/upload
rm *.*
cd $AGENT_HOME/sysman/emd/state
rm *.*

No need to remove storage directory under $AGENT_HOME/sysman/emd/state

cd $AGENT_HOME/bin
./emctl start agent
./emctl status agent

(source: http://gavinsoorma.wordpress.com/2009/12/03/how-to-manually-clear-em-grid-control-alerts/)