Server error while convert into PDF

Frappe Framework Print Formats
1

Server Error

Traceback (innermost last):
  File "/home/frappe/frappe-bench/apps/frappe/frappe/app.py", line 60, in application
    response = frappe.api.handle()
  File "/home/frappe/frappe-bench/apps/frappe/frappe/api.py", line 50, in handle
    return frappe.handler.handle()
  File "/home/frappe/frappe-bench/apps/frappe/frappe/handler.py", line 19, in handle
    execute_cmd(cmd)
  File "/home/frappe/frappe-bench/apps/frappe/frappe/handler.py", line 36, in execute_cmd
    ret = frappe.call(method, **frappe.form_dict)
  File "/home/frappe/frappe-bench/apps/frappe/frappe/__init__.py", line 806, in call
    return fn(*args, **newargs)
  File "/home/frappe/frappe-bench/apps/frappe/frappe/templates/pages/print.py", line 182, in download_pdf
    frappe.local.response.filecontent = get_pdf(html)
  File "/home/frappe/frappe-bench/apps/frappe/frappe/utils/pdf.py", line 16, in get_pdf
    pdfkit.from_string(html, fname, options=options or {})
  File "/home/frappe/frappe-bench/env/src/pdfkit/pdfkit/api.py", line 68, in from_string
    return r.to_pdf(output_path)
  File "/home/frappe/frappe-bench/env/src/pdfkit/pdfkit/pdfkit.py", line 143, in to_pdf
    raise IOError("wkhtmltopdf exited with non-zero code {0}. error:\n{1}".format(exit_code, stderr.decode("utf-8")))
 IOError: wkhtmltopdf exited with non-zero code -6. error:
The switch --no-outline, is not support using unpatched qt, and will be ignored.The switch --header-html, is not support using unpatched qt, and will be ignored.The switch --footer-html, is not support using unpatched qt, and will be ignored.The switch --print-media-type, is not support using unpatched qt, and will be ignored.QXcbConnection: Could not connect to display
2

hi @sethu,
please see this link

Thanks