Just to give a sample and one of the ways to implement this: I created an approval process, just added an action to update any field. In your case it will be your specific field. [![DummyApprovalprocess][1]][1] After that just wrote a trigger on Opportunity `beforeUpdate` like this. You can add your conditions. trigger OpportunityTrigger on Opportunity (before update) { if(trigger.isUpdate && trigger.isBefore) { for(Opportunity s : Trigger.new){ s.addError('You must add at least one osr Product to your Request'); } } } And when submitting for approval: [![enter image description here][2]][2] got this message: [![enter image description here][3]][3] Not you will have to fix your code for compilation errors and all, but this was just to show that this flow does work and allows us to put a validation in approval process. [1]: https://i.sstatic.net/WOKvm.png [2]: https://i.sstatic.net/VDOlZ.png [3]: https://i.sstatic.net/UBkbk.png