Odoo Server Error
Traceback (most recent call last):
  File "c:\program files (x86)\odoo 12.0\server\odoo\addons\web\controllers\main.py", line 1671, in report_download
    response = self.report_routes(reportname, docids=docids, converter=converter)
  File "C:\Program Files (x86)\Odoo 12.0\server\odoo\http.py", line 517, in response_wrap
    response = f(*args, **kw)
  File "c:\program files (x86)\odoo 12.0\server\odoo\addons\web\controllers\main.py", line 1612, in report_routes
    pdf = report.with_context(context).render_qweb_pdf(docids, data=data)[0]
  File "c:\program files (x86)\odoo 12.0\server\odoo\addons\base\models\ir_actions_report.py", line 687, in render_qweb_pdf
    bodies, html_ids, header, footer, specific_paperformat_args = self.with_context(context)._prepare_html(html)
  File "c:\program files (x86)\odoo 12.0\server\odoo\addons\base\models\ir_actions_report.py", line 309, in _prepare_html
    root = lxml.html.fromstring(html)
  File "C:\Program Files (x86)\Odoo 12.0\python\lib\site-packages\lxml\html\__init__.py", line 876, in fromstring
    doc = document_fromstring(html, parser=parser, base_url=base_url, **kw)
  File "C:\Program Files (x86)\Odoo 12.0\python\lib\site-packages\lxml\html\__init__.py", line 765, in document_fromstring
    "Document is empty")
lxml.etree.ParserError: Document is empty