Do you really want to convert your opportunity through trigger or on Button action click. If you are choosing trigger then your logic should be like trigger OnOpprtunityUpdate on Opportunity(before update){ Set accId = new Set(); List opplist = new List(); List conrtlist = new List(); for(Opportunity opp : Trigger.new){ if(opp.StageName == 'Closed Won'){ Contract con = new Contract(); if(opp.AccountId != NULL){ con .AccountId = opp.AccountId; } con .Status = 'Draft'; con .StartDate = System.Today(); con .ContractTerm = opp.Length_of_project_months__c; con.X2_RESEARCH_LPA__c = opp.X2_RESEARCH_LPA__c con.X3_RESEARCH_site_history__c) - opp.X3_RESEARCH_site_history__c) con.X4_RESEARCH_likely_issues__c = opp.X4_RESEARCH_likely_issues__c con.X5_RESEARCH_Stakeholders__c - opp.X5_RESEARCH_Stakeholders__c con.X6_RESEARCH_company_other_projects__c = opp.X6_RESEARCH_company_other_projects__c con.Client_Code__c = opp.Client_Code__c con.Council__c = opp.Council__c con.Date_for_1st_Public_Exhibition__c = opp.Date_for_1st_Public_Exhibition__c con.Date_for_2nd_Public_Exhibition__c = opp.Date_for_2nd_Public_Exhibition__c con.Date_to_Call__c = opp.Date_to_Call__c con.Date_for_Submission__c = opp.Date_for_Submission__c con.Details_of_Lead__c = opp.Details_of_Lead__c con.First_Meeting_Report__c = opp.First_Meeting_Report__c con.IPA_Pitch_Member_1__c = opp.IPA_Pitch_Member_1__c con.IPA_Pitch_Member_2__c = opp.IPA_Pitch_Member_2__c con.IPA_Pitch_Member_3__c = opp.IPA_Pitch_Member_3__c con.Indigo_Email__c = opp.Indigo_Email__c con.Planning_Committee_Date_Time__c = opp.Planning_Committee_Date_Time__c con.Previous_contact__c = opp.Previous_contact__c con.Referersemail__c = opp.Referersemail__c con.Region__c = opp.Region__c con.Relevant_Work__c = opp.Relevant_Work__c con.Sales_Notes__c = opp.Sales_Notes__c con.Sector__c = opp.Sector__c con.Is_there_a_URL_where_you_found_this_lead__c = opp.Is_there_a_URL_where_you_found_this_lead__c conrtlist .add(con ); } } if(conrtlist.size() > 0){ insert conrtlist ; } }

Thank you very much for this.

I just tried this, adding the line you suggested in (see full code below), using Force.com IDE

Frustratingly, I am getting a failure - here is the error log.

Your advice most welcome.

*** Deployment Log ***

Result: FAILED

Date: September 11, 2013 1:01:28 PM BST

# Deployed From:

   Project name: Contracts

   Username: alex.ritson@indigopa.com

   Endpoint: www.salesforce.com

# Deployed To:

   Username: alex.ritson@indigopa.com

   Endpoint: www.salesforce.com

# Deploy Results:

   File Name:    package.xml

   Full Name:  package.xml

   Action:  NO ACTION

   Result:  FAILED

   Problem: Cannot deploy InstalledPackage in Package Manifest with any other types!

# Test Results:

   n/a

public with sharing class CreatecontractonOppstageclosewon {
trigger CreatecontractonOppstageclosewon on Opportunity (after insert , after update) 
{
Set<Id> accId = new Set<Id>();
List<Opportunity> opplist = new List<Opportunity>();
List<contract> conrtlist = new List<contract>();
for(Opportunity opp : Trigger.new){
if(opp.StageName == 'Closed Won'){
Contract con = new Contract();
if(opp.AccountId != NULL){
con .AccountId = opp.AccountId;
}
con .Status = 'Draft';
con .StartDate = System.Today();
con .ContractTerm = opp.Length_of_project_months__c;
con.X2_RESEARCH_LPA__c = opp.X2_RESEARCH_LPA__c
con.X3_RESEARCH_site_history__c) - opp.X3_RESEARCH_site_history__c)
con.X4_RESEARCH_likely_issues__c = opp.X4_RESEARCH_likely_issues__c
con.X5_RESEARCH_Stakeholders__c - opp.X5_RESEARCH_Stakeholders__c
con.X6_RESEARCH_company_other_projects__c = opp.X6_RESEARCH_company_other_projects__c
con.Client_Code__c = opp.Client_Code__c
con.Council__c = opp.Council__c
con.Date_for_1st_Public_Exhibition__c = opp.Date_for_1st_Public_Exhibition__c
con.Date_for_2nd_Public_Exhibition__c = opp.Date_for_2nd_Public_Exhibition__c
con.Date_to_Call__c = opp.Date_to_Call__c
con.Date_for_Submission__c = opp.Date_for_Submission__c
con.Details_of_Lead__c = opp.Details_of_Lead__c
con.First_Meeting_Report__c = opp.First_Meeting_Report__c
con.IPA_Pitch_Member_1__c = opp.IPA_Pitch_Member_1__c
con.IPA_Pitch_Member_2__c = opp.IPA_Pitch_Member_2__c
con.IPA_Pitch_Member_3__c = opp.IPA_Pitch_Member_3__c
con.Indigo_Email__c = opp.Indigo_Email__c
con.Planning_Committee_Date_Time__c = opp.Planning_Committee_Date_Time__c
con.Previous_contact__c = opp.Previous_contact__c
con.Referersemail__c = opp.Referersemail__c
con.Region__c = opp.Region__c
con.Relevant_Work__c = opp.Relevant_Work__c
con.Sales_Notes__c = opp.Sales_Notes__c
con.Sector__c = opp.Sector__c
con.Is_there_a_URL_where_you_found_this_lead__c = opp.Is_there_a_URL_where_you_found_this_lead__c
conrtlist .add(con );
}
}
if(conrtlist.size() > 0){
insert conrtlist ;
}
}
}