I am having few validation rules on Opportunity, which should be fired when
"Closed Won". An example validation rule is shown below
AND ( ISPICKVAL(StageName, 'Closed Won'), ISBLANK( SomeOppField__c ) )
Opportunity > StageName = "Closed Won" happens after Approval > Field Update.
Somehow none of the validation rule fires after Opportunity is approved to closed won, my requirement is to block approval process, if data on opportunity is missing.
Approvedare two entirely different things. If you're moving to
Closed-wonas part of your Approval process, then you likely need to separate the two. I don't believe you can have a validation rule fire on an approval process. That runs under an entirely different context than when a typical user saves a record.