Hi Everyone,

Just started coding with APEX last week and am trying to create a trigger that whenever an account field is edited, it looks into the opportunities of the account that has been edited. From the account's opportunities, it updates (see code below) a field labeled "Next Renewable Opportunity" when the opportunity is the account's next opportunity to be renewed. 
 

trigger CheckForNextRenewableOpp on Account(after insert, after update) {   
    // Get the related opportunities for the accounts in this trigger.        
    List<Opportunity> relatedOpps = [SELECT Id,Name,Contract_Expiration_Date__c, Next_Renewable_Opportunity__c FROM Opportunity
        WHERE Contract_Expiration_Date__c__c != NULL AND AccountID IN :Trigger.New];          
    // Iterate over the related opportunities
   for(Opportunity opp : relatedOpps) {      
       if (Account.Next_Renewal_Date__c != Null){
            if ((date.valueof(opp.Contract_Expiration_Date__c) == date.valueOf(Account.Next_Renewal_Date__c) ) && (Opp.Next_Renewable_Opportunity__c == False)){
                opp.Next_Renewable_Opportunity__c = True; // Sets next renewable opportunity field to 'TRUE' 
                update opp;
            }
            else if (((date.valueof(opp.Contract_Expiration_Date__c) < Date.today()) || (date.valueof(opp.Contract_Expiration_Date__c) != date.valueOf(Account.Next_Renewal_Date__c)))
                     && (opp.Next_Renewable_Opportunity__c == True)){                       
                         opp.Next_Renewable_Opportunity__c = False; // Sets next renewable oppotuinity field to 'False'
                         update opp;
                     }
       }
   }
}

// Contract Expiration Date: Opportunity Field, Type: Date Field
// Next Renewal Date: Account Field, Type: Rollup Summary Field
// Next Renewable Opportunity: Opportunity Field, Type: Checkbox Field

Please Advise.  When I run the trigger I get this error:

Error:Apex trigger CheckForNextRenewableOpp caused an unexpected exception, contact your administrator: CheckForNextRenewableOpp: execution of AfterUpdate caused by: System.TypeException: Invalid date: common.apex.runtime.impl.ApexFieldToken@3c8ccc3b: ()

Thanking you in advance, 
FD