Hello Uwe,Thanks for reply.I will try ORA-00600-Troubleshooting Tool I tried to recover database because I had a block corruption shown at the alert log file. But I couldn't upload log files here because uploading contents is not allowed at that moment.Regards, On Sunday, November 30, 2014 2:29 PM, Uwe Küchler <uwe@xxxxxxxxxxxx> wrote: Mostafa, as for the ORA-600 you should try the “ORA-00600-Troubleshooting Tool” on My Oracle Support for a suggestion. Upload the corresponding trace file or an IPS package and see what the tool comes up with. As for the recovery error, you didn't provide us with much information. Why did you have to "recover database" in the first place? Could it be that your database is already open instead of just mounted? Regards, Uwe --- http://oraculix.com/ On 30.11.2014 11:55, Mostafa Eletriby (Redacted sender m_etrib@xxxxxxxxx for DMARC) wrote: Hello DBAs, I have a problem regarding Ora-600 error at Alert log file. It appears regularly at alert log file and stops database and needs to re-open database. Please tell me which procedures that I should follow in order to solve the problem. Database has no previous backup taken. Database was in no archive mode before problem happened but now it is switched to archive log mode ------------------------------------ SQL> recover database; ORA-00283: recovery session canceled due to errors ORA-01124: cannot recover data file 1 - file is in use or recovery ORA-01110: data file 1: '/oraData/cdsdb/system01.dbf' Please advice me. Thanks Regards,