Dropbox backups email issue on multitenant sites

After upgrading version v8 to v10 i have faceing below issue for dropbox backups.
I have dropbox setup Multitenant sites. I have dropbox backup frequeuency should be daily.
All sites backup properly on dropbox but not mail sent to backup successufully uploaded.
Two sites backup mail sent two successfully uploaded mail sent.
This one site data size big(160 MB) compaire two other two site. This one site sent mail backup uploaded fail and show below error.

    Backup Upload Failed
    Oops, your automated backup to Dropbox failed.

    Error message: 
    ./erp.logicaresystems.com/private/files/Production_batch_shortage_report_03.09.18..xlsx - Traceback (most recent call last):
      File "/home/erp1/ERPNext/frappe-bench/apps/frappe/frappe/integrations/doctype/dropbox_settings/dropbox_settings.py", line 145, in upload_from_folder
        upload_file_to_dropbox(filepath, dropbox_folder, dropbox_client)
      File "/home/erp1/ERPNext/frappe-bench/apps/frappe/frappe/integrations/doctype/dropbox_settings/dropbox_settings.py", line 166, in upload_file_to_dropbox
        dropbox_client.files_upload(f.read(), path, mode)
      File "/home/erp1/ERPNext/frappe-bench/env/local/lib/python2.7/site-packages/dropbox/base.py", line 1267, in files_upload
        f,
      File "/home/erp1/ERPNext/frappe-bench/env/local/lib/python2.7/site-packages/dropbox/dropbox.py", line 239, in request
        timeout=timeout)
      File "/home/erp1/ERPNext/frappe-bench/env/local/lib/python2.7/site-packages/dropbox/dropbox.py", line 330, in request_json_string_with_retry
        timeout=timeout)
      File "/home/erp1/ERPNext/frappe-bench/env/local/lib/python2.7/site-packages/dropbox/dropbox.py", line 414, in request_json_string
        timeout=timeout,
      File "/home/erp1/ERPNext/frappe-bench/env/local/lib/python2.7/site-packages/requests/sessions.py", line 559, in post
        return self.request('POST', url, data=data, json=json, **kwargs)
      File "/home/erp1/ERPNext/frappe-bench/env/local/lib/python2.7/site-packages/requests/sessions.py", line 512, in request
        resp = self.send(prep, **send_kwargs)
      File "/home/erp1/ERPNext/frappe-bench/env/local/lib/python2.7/site-packages/requests/sessions.py", line 622, in send
        r = adapter.send(request, **kwargs)
      File "/home/erp1/ERPNext/frappe-bench/env/local/lib/python2.7/site-packages/requests/adapters.py", line 445, in send
        timeout=timeout
      File "/home/erp1/ERPNext/frappe-bench/env/local/lib/python2.7/site-packages/urllib3/connectionpool.py", line 600, in urlopen
        chunked=chunked)
      File "/home/erp1/ERPNext/frappe-bench/env/local/lib/python2.7/site-packages/urllib3/connectionpool.py", line 377, in _make_request
        httplib_response = conn.getresponse(buffering=True)
      File "/usr/lib/python2.7/httplib.py", line 1136, in getresponse
        response.begin()
      File "/usr/lib/python2.7/httplib.py", line 453, in begin
        version, status, reason = self._read_status()
      File "/usr/lib/python2.7/httplib.py", line 409, in _read_status
        line = self.fp.readline(_MAXLINE + 1)
      File "/usr/lib/python2.7/socket.py", line 480, in readline
        data = self._sock.recv(self._rbufsize)
      File "/home/erp1/ERPNext/frappe-bench/env/local/lib/python2.7/site-packages/urllib3/contrib/pyopenssl.py", line 276, in recv
        if not util.wait_for_read(self.socket, self.socket.gettimeout()):
      File "/home/erp1/ERPNext/frappe-bench/env/local/lib/python2.7/site-packages/urllib3/util/wait.py", line 146, in wait_for_read
        return wait_for_socket(sock, read=True, timeout=timeout)
      File "/home/erp1/ERPNext/frappe-bench/env/local/lib/python2.7/site-packages/urllib3/util/wait.py", line 107, in poll_wait_for_socket
        return bool(_retry_on_intr(do_poll, timeout))
      File "/home/erp1/ERPNext/frappe-bench/env/local/lib/python2.7/site-packages/urllib3/util/wait.py", line 56, in _retry_on_intr
        return fn(timeout)
      File "/home/erp1/ERPNext/frappe-bench/env/local/lib/python2.7/site-packages/urllib3/util/wait.py", line 105, in do_poll
        return poll_obj.poll(t)
      File "/home/erp1/ERPNext/frappe-bench/env/local/lib/python2.7/site-packages/rq/timeouts.py", line 64, in handle_death_penalty
        '({0} seconds)'.format(self._timeout))
    JobTimeoutException: Task exceeded maximum timeout value (1500 seconds)

    Traceback (most recent call last):
      File "/home/erp1/ERPNext/frappe-bench/apps/frappe/frappe/integrations/doctype/dropbox_settings/dropbox_settings.py", line 48, in take_backup_to_dropbox
        if did_not_upload: raise Exception
    ExceptionPreformatted text
    Please contact your system manager for more information.

After I have above issue faceing execute in crontab below method :
For Ex.
*/5 * * * * cd /home/erp/ERPNext/frappe-bench && /home/erp/ERPNext/bin/bench --site all execute frappe.integrations.doctype.dropbox_setting.dropbox_settings.take_backups_daily >> /home/erp1/ERPNext/frappe-bench/logs/dropboxcrontab.log 2>&1

After above method execute all site backups successfully uploaded dropbox 12.05 am.
But two site sent mail successfully uploaded data and other one site data uploaded fail.
But 5:30 am again one mail sent two backups upload successfully for all three site.
So Kindly suggest some solution to overcome this issue…

Please suggest the solution…

Please awaiting the suggestions…

have you found any solution?