If ORACLE IAS Report server won't start

If you tried everything and still you cannot start reports service on you Oracle IAS - assuming that you did not made any configuration change, then following should help you:

opmnctl stopall

cd $ORACLE_HOME\reports\server\

mv repXXXXXXX.dat repXXXXXXX.dat.old (where XXX is the name of your reports server)

opmnctl startall

If this *.dat file somehow became inconsistent or corrupted, then IAS Reports server fail to start. Simple delete or renaming of old dat file will solve the problem. After restarting with opmnctl, appropriate dat file will be re-generated.