Hi, 

I have created a select screen where the user selects a type of object and then can download a CSV that is created on a different page based on parameters of the object. Everything is working fine except for when I try to use window.open() from this page to open up the page that automatically downloads the CSV.

The error I am getting is:

java.lang.IllegalArgumentException: Illegal view ID window.open(/apex/generatespreadsheet?id=a08i0000000SFrtAAG). The ID must begin with /

If I copy the URL in the window.open to the browser, it works fine.

I'm not quite sure what the problem is about, but I've tried numerous ways to solve it. 

Anyone here have any thoughts?

Thanks.

<apex:page controller="DownloadCSV" tabstyle="Function__c" showHeader="false" sidebar="false">
<script>
 function closeSearchWindow()
 {
    window.close();
 }
 function x(){
 calldownloader();
 }
</script>
<apex:form >
<apex:actionFunction name="calldownloader" action="{!downloader}" rerender=""/>
 <apex:pageblock title="Data Spreadsheet" mode="edit" id="Everything">
<apex:pageBlockSection columns="1">
        <apex:pagemessages />
        <apex:inputField value="{!sheet.Scenario__c}" required="true"  onChange="x();"/>
      <apex:commandbutton rerender="Everything" value="rerender" />
         <apex:commandbutton action="window.open('{!placetogo}')" value="Create" />
 </apex:pageblocksection>
 
  </apex:pageblock>
  </apex:form>
</apex:page>

public class DownloadCSV {
public Data_SpreadSheet__c sheet{get;set;}
public String placetogo{get;set;}
Pagereference pref{get;set;}

public DownloadCSV(){
sheet=new Data_SpreadSheet__c();
}

public void downloader(){

pref = new Pagereference('/apex/generatespreadsheet?id='+sheet.Scenario__c);

placetogo='/apex/generatespreadsheet?id='+sheet.Scenario__c;

}

}