Osama_mustafa wrote:My Database is Oracle 11g R2 & OS Version is Windows Server 2008 R2 Standard..
Refer to MOS notes :
ORA 01555 "snapshot too old: rollback segment number %s with name \"%s\" too small" [ID 1555.1]
ORA-01555: snapshot too old - Causes and Solutions [ID 1005107.6]
Also Remember when you post your thread always Post DB version , OS Version