This is the full error from the logs:

2017-10-18 11:03:15,019 3974 ERROR pbdevdb2 werkzeug: Error on request:
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/werkzeug/serving.py", line 177, in run_wsgi
    execute(self.server.app)
  File "/usr/lib/python2.7/dist-packages/werkzeug/serving.py", line 165, in execute
    application_iter = app(environ, start_response)
  File "/usr/lib/python2.7/dist-packages/openerp/service/wsgi_server.py", line 184, in application
    return application_unproxied(environ, start_response)
  File "/usr/lib/python2.7/dist-packages/openerp/service/wsgi_server.py", line 170, in application_unproxied
    result = handler(environ, start_response)
  File "/usr/lib/python2.7/dist-packages/openerp/http.py", line 1497, in __call__
    return self.dispatch(environ, start_response)
  File "/usr/lib/python2.7/dist-packages/openerp/http.py", line 1471, in __call__
    return self.app(environ, start_wrapped)
  File "/usr/lib/python2.7/dist-packages/werkzeug/wsgi.py", line 579, in __call__
    return self.app(environ, start_response)
  File "/usr/lib/python2.7/dist-packages/openerp/http.py", line 1668, in dispatch
    result = ir_http._dispatch()
  File "/usr/lib/python2.7/dist-packages/openerp/addons/utm/models/ir_http.py", line 15, in _dispatch
    response = super(ir_http, self)._dispatch()
  File "/usr/lib/python2.7/dist-packages/openerp/addons/web_editor/models/ir_http.py", line 16, in _dispatch
    return super(ir_http, self)._dispatch()
  File "/usr/lib/python2.7/dist-packages/openerp/addons/base/ir/ir_http.py", line 187, in _dispatch
    return self._handle_exception(e)
  File "/usr/lib/python2.7/dist-packages/openerp/addons/base/ir/ir_http.py", line 158, in _handle_exception
    return request._handle_exception(exception)
  File "/usr/lib/python2.7/dist-packages/openerp/http.py", line 788, in _handle_exception
    return super(HttpRequest, self)._handle_exception(exception)
  File "/usr/lib/python2.7/dist-packages/openerp/addons/base/ir/ir_http.py", line 183, in _dispatch
    result = request.dispatch()
  File "/usr/lib/python2.7/dist-packages/openerp/http.py", line 847, in dispatch
    r = self._call_function(**self.params)
  File "/usr/lib/python2.7/dist-packages/openerp/http.py", line 323, in _call_function
    return checked_call(self.db, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/openerp/service/model.py", line 118, in wrapper
    return f(dbname, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/openerp/http.py", line 316, in checked_call
    result = self.endpoint(*a, **kw)
  File "/usr/lib/python2.7/dist-packages/openerp/http.py", line 966, in __call__
    return self.method(*args, **kw)
  File "/usr/lib/python2.7/dist-packages/openerp/http.py", line 516, in response_wrap
    response = f(*args, **kw)
  File "/usr/lib/python2.7/dist-packages/openerp/addons/connector/controllers/main.py", line 90, in runjob
    self._try_perform_job(session_hdl, job)
  File "/usr/lib/python2.7/dist-packages/openerp/addons/connector/controllers/main.py", line 66, in _try_perform_job
    job.perform(session)
  File "/usr/lib/python2.7/dist-packages/openerp/addons/connector/queue/job.py", line 493, in perform
    self.result = self.func(session, *self.args, **self.kwargs)
  File "/usr/lib/python2.7/dist-packages/openerp/addons/connector_prestashop/unit/importer.py", line 517, in import_record
    return importer.run(prestashop_id, **kwargs)
  File "/usr/lib/python2.7/dist-packages/openerp/addons/connector_prestashop/unit/importer.py", line 256, in run
    self._import_dependencies()
  File "/usr/lib/python2.7/dist-packages/openerp/addons/connector_prestashop/models/sale_order/importer.py", line 324, in _import_dependencies
    self.line_template_errors.push(row)
AttributeError: 'list' object has no attribute 'push'