返回代码500的javascript URLfetchApp请求失败

Question

我正在处理某些事情，当我使用URLfetchApp时 当我运行该程序时，它说“请求失败”并返回代码500。

这是我的代码：

var ss = SpreadsheetApp.openById("1zTdSwuZX1oY6_wBqHjlzSkNkTA8Zopa6DQ0OkkTofH0");
  
  var url = "https://docs.google.com/spreadsheets/d/SS_ID/export?".replace("SS_ID", ss.getId());
  
  var url_ext = 'exportFormat=pdf&format=pdf'        // export as pdf / csv / xls / xlsx
  + '&size=letter'                       // paper size legal / letter / A4
  + '&portrait=false'                    // orientation, false for landscape
  + '&fitw=true&source=labnol'           // fit to page width, false for actual size
  + '&sheetnames=false&printtitle=false' // hide optional headers and footers
  + '&pagenumbers=false&gridlines=false' // hide page numbers and gridlines
  + '&fzr=false'                         // do not repeat row headers (frozen rows) on each page
  + '&gid=';                             // the sheet's Id
  
  var token = ScriptApp.getOAuthToken();
  var sheets = ss.getSheets();
  var folder = DriveApp.getFolderById("0Bw9Go3RUhtd0UW1RY1M3NE1OUmM");
  var blobs = [];
  
  var params = { headers: { 'Authorization': 'Bearer ' +  token }};
  
  for (var i=0; i<sheets.length; i++) {
    
    // Convert individual worksheets to PDF
    var response = UrlFetchApp.fetch(url + url_ext + sheets[i].getSheetId(), params);
    
     blobs[i] = response.getBlob().setName(sheets[i].getName() + '.pdf');
    
    folder.createFile(blobs[i]);
  }

请帮帮我:)。