I am using Odoo V16 onlöine enterprise. 
I am getting following error while closing PoS Session:

RPC_ERROR

Odoo Server Error

Traceback (most recent call last):
  File "/home/odoo/src/odoo/saas-16.1/odoo/http.py", line 1686, in _serve_db
    return service_model.retrying(self._serve_ir_http, self.env)
  File "/home/odoo/src/odoo/saas-16.1/odoo/service/model.py", line 134, in retrying
    result = func()
  File "/home/odoo/src/odoo/saas-16.1/odoo/http.py", line 1713, in _serve_ir_http
    response = self.dispatcher.dispatch(rule.endpoint, args)
  File "/home/odoo/src/odoo/saas-16.1/odoo/http.py", line 1911, in dispatch
    result = self.request.registry['ir.http']._dispatch(endpoint)
  File "/home/odoo/src/odoo/saas-16.1/addons/website/models/ir_http.py", line 234, in _dispatch
    response = super()._dispatch(endpoint)
  File "/home/odoo/src/odoo/saas-16.1/odoo/addons/base/models/ir_http.py", line 154, in _dispatch
    result = endpoint(**request.params)
  File "/home/odoo/src/odoo/saas-16.1/odoo/http.py", line 715, in route_wrapper
    result = endpoint(self, *args, **params_ok)
  File "/home/odoo/src/odoo/saas-16.1/addons/web/controllers/dataset.py", line 32, in call_button
    action = self._call_kw(model, method, args, kwargs)
  File "/home/odoo/src/odoo/saas-16.1/addons/web/controllers/dataset.py", line 24, in _call_kw
    return call_kw(request.env[model], method, args, kwargs)
  File "/home/odoo/src/odoo/saas-16.1/odoo/api.py", line 461, in call_kw
    result = _call_kw_multi(method, model, args, kwargs)
  File "/home/odoo/src/odoo/saas-16.1/odoo/api.py", line 448, in _call_kw_multi
    result = method(recs, *args, **kwargs)
  File "/home/odoo/src/odoo/saas-16.1/addons/point_of_sale/models/pos_session.py", line 268, in action_pos_session_closing_control
    return session.action_pos_session_validate(balancing_account, amount_to_balance, bank_payment_method_diffs)
  File "/home/odoo/src/odoo/saas-16.1/addons/point_of_sale/models/pos_session.py", line 273, in action_pos_session_validate
    return self.action_pos_session_close(balancing_account, amount_to_balance, bank_payment_method_diffs)
  File "/home/odoo/src/odoo/saas-16.1/addons/point_of_sale/models/pos_session.py", line 280, in action_pos_session_close
    return self._validate_session(balancing_account, amount_to_balance, bank_payment_method_diffs)
  File "/home/odoo/src/enterprise/saas-16.1/l10n_de_pos_cert/models/pos_session.py", line 58, in _validate_session
    json = self._l10n_de_create_cash_point_closing_json(orders)
  File "/home/odoo/src/enterprise/saas-16.1/l10n_de_pos_cert/models/pos_session.py", line 111, in _l10n_de_create_cash_point_closing_json
    return ast.literal_eval(json.strip())
  File "/home/odoo/src/odoo/saas-16.1/odoo/tools/_monkeypatches.py", line 48, in literal_eval
    raise ValueError("expression can't exceed buffer limit")
ValueError: expression can't exceed buffer limit

The above server error caused the following client error:
RPC_ERROR: Odoo Server Error
    at makeErrorFromResponse (https://www.namastedeutschland.de/web/assets/10268-5831f36/web.assets_backend.min.js:993:163)
    at XMLHttpRequest. (https://www.namastedeutschland.de/web/assets/10268-5831f36/web.assets_backend.min.js:1001:13)