I'm suddenly getting this error when pushing unrelated code to production. The class in question has been working fine for over a year. The error lines are anywhere it says tstcont.submitCase();

@isTest
class TestWeb2CaseCont {
    static testMethod void testCaseWithContact(){
        Account a = TestUtils.getAccount('ut Acc1');
        insert a;
        Contact ct = TestUtils.getContact(a, 'ut Contact1');
        ct.Email = 'utContact1@testclass.com';
        insert ct;
       
        Web2CaseCont tstcont = new Web2CaseCont();
        tstcont.c.SuppliedEmail = ct.Email;
        tstcont.submitCase();
        System.assertEquals(ct.Id, tstcont.c.ContactId);
        System.assertEquals(a.Id, tstcont.c.AccountId);
    }
   
    static testMethod void testCaseWithoutContact(){       
        Web2CaseCont tstcont = new Web2CaseCont();
        tstcont.submitCase();
        System.assertEquals(tstcont.c.ContactId, null);
        System.assertEquals(tstcont.c.AccountId, null);
    }
   
    static testMethod void testPageParameters(){       
        Test.setCurrentPageReference(new PageReference('Page.Web2Case'));
        System.currentPageReference().getParameters().put('pline', 'None');
        System.currentPageReference().getParameters().put('Origin', 'None');
        System.currentPageReference().getParameters().put('co', 'None');       
       
        Web2CaseCont tstcont = new Web2CaseCont();
        tstcont.submitCase();
        System.assertEquals(tstcont.c.Product_Line__c,'None' );
        System.assertEquals(tstcont.c.Origin,'None' );
        System.assertEquals(tstcont.c.SuppliedCompany,'None' );
    }
   
    static testMethod void testAttachment(){       
        Attachment att = new Attachment();
        att.Name = 'ut attachment';
        att.Body = Blob.valueOf(att.Name);
        Web2CaseCont tstcont = new Web2CaseCont();
        tstCont.att = att;
        tstcont.submitCase();
    }
   
    static testMethod void testFailure(){          
        Web2CaseCont tstcont = new Web2CaseCont();
        tstcont.c = null;
        tstcont.submitCase();
        System.assertEquals(tstcont.msg, System.label.WebCaseFailure );
    }
}