Odoo migration 13EE -> 16EE is in the test phase. Ecommerce does not work when there is a problem with the carousel of product images after migration. The error message comes when I try to open the product page. How can I solve this problem?

500: Internal Server Error

Traceback (most recent call last):
File "<1658>", line 137, in template_1658
File "<1658>", line 111, in template_1658_content
TypeError: object of type 'NoneType' has no len()

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
File "/opt/odoo/odoo/odoo/http.py", line 1587, in _serve_db
return service_model.retrying(self._serve_ir_http, self.env)
File "/opt/odoo/odoo/odoo/service/model.py", line 134, in retrying
result = func()
File "/opt/odoo/odoo/odoo/http.py", line 1614, in _serve_ir_http
response = self.dispatcher.dispatch(rule.endpoint, args)
File "/opt/odoo/odoo/odoo/http.py", line 1727, in dispatch
return self.request.registry['ir.http']._dispatch(endpoint)
File "/opt/odoo/odoo/addons/website/models/ir_http.py", line 235, in _dispatch
response = super()._dispatch(endpoint)
File "/opt/odoo/odoo/odoo/addons/base/models/ir_http.py", line 156, in _dispatch
result.flatten()
File "/opt/odoo/odoo/odoo/http.py", line 1102, in flatten
self.response.append(self.render())
File "/opt/odoo/odoo/odoo/http.py", line 1094, in render
return request.env["ir.ui.view"]._render_template(self.template, self.qcontext)
File "/opt/odoo/odoo/addons/website/models/ir_ui_view.py", line 418, in _render_template
return super()._render_template(template, values=values)
File "/opt/odoo/odoo/odoo/addons/base/models/ir_ui_view.py", line 2128, in _render_template
return self.env['ir.qweb']._render(template, values)
File "/opt/odoo/odoo/odoo/tools/profiler.py", line 292, in _tracked_method_render
return method_render(self, template, values, **options)
File "/opt/odoo/odoo/odoo/addons/base/models/ir_qweb.py", line 580, in _render
result = ''.join(rendering)
File "<3742>", line 1225, in template_3742
File "<3742>", line 1207, in template_3742_content
File "<3742>", line 254, in template_3742_t_call_0
File "<1658>", line 143, in template_1658
odoo.addons.base.models.ir_qweb.QWebException: Error while render the template
TypeError: object of type 'NoneType' has no len()
Template: website_sale.shop_product_carousel
Path: /t/div/div/t
Node: