Oracle Enterprise Manager – Where do I find the error logs

oracleoracle-11g-r2

I'm not familiar with oracle management. The problem is when I try to connect to the enterprise manager through the Web browser I get this error:

enter image description here

In english: "Internal Error has occurred. Check the log file for details."

Where to find the log file to see what's the problem?

I'm using Windows 7 and Oracle 11gR2 EE.

ORACLE_HOME/HOSTNAME_SID/sysman/log

... is where I finally found them. I don't know if this is system dependent; this was on a linux box.

a) you need a command prompt with elevated privileges (run as administrator) to do this

b) alternatively, you can start the service from Windows GUI (services.msc)

Why do you use the -cluster - option ?
Is you database repository part of a cluster ?

Make sure first that you can connect to the database using the tns names.

Example :

sqlplus system/password@'tns_identified'

Then to deconfig you em repo :
Try using this syntax :

 emca -deconfig dbcontrol db -repos drop -SYS_PWD oracle -SYSMAN_PWD oracle