A deployment of mailman with posterius (v1.3.10) gives a 500 error when rendering a mailing list page with a non-empty `info` field. The `info` field is attempted to be rendered as markdown. See [summary.html#L20](https://gitlab.com/mailman/postorius/-/blob/master/src/postorius/templates/postorius/lists/summary.html?ref_type=heads#L20). This is the backtrace: ``` Internal Server Error: /postorius/lists/mailman.lists.example.com/ Traceback (most recent call last): File "/nix/store/lgnzdwq1kk6lr6wpwz77sa233lkj4hni-python3-3.11.9-env/lib/python3.11/site-packages/django/core/handlers/exception.py", line 55, in inner response = get_response(request) ^^^^^^^^^^^^^^^^^^^^^ File "/nix/store/lgnzdwq1kk6lr6wpwz77sa233lkj4hni-python3-3.11.9-env/lib/python3.11/site-packages/django/core/handlers/base.py", line 197, in _get_response response = wrapped_callback(request, *callback_args, **callback_kwargs) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/nix/store/lgnzdwq1kk6lr6wpwz77sa233lkj4hni-python3-3.11.9-env/lib/python3.11/site-packages/django/views/generic/base.py", line 104, in view return self.dispatch(request, *args, **kwargs) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/nix/store/lgnzdwq1kk6lr6wpwz77sa233lkj4hni-python3-3.11.9-env/lib/python3.11/site-packages/postorius/views/generic.py", line 76, in dispatch return super(MailingListView, self).dispatch(request, *args, **kwargs) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/nix/store/lgnzdwq1kk6lr6wpwz77sa233lkj4hni-python3-3.11.9-env/lib/python3.11/site-packages/django/views/generic/base.py", line 143, in dispatch return handler(request, *args, **kwargs) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/nix/store/lgnzdwq1kk6lr6wpwz77sa233lkj4hni-python3-3.11.9-env/lib/python3.11/site-packages/postorius/views/list.py", line 414, in get return render(request, 'postorius/lists/summary.html', data) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/nix/store/lgnzdwq1kk6lr6wpwz77sa233lkj4hni-python3-3.11.9-env/lib/python3.11/site-packages/django/shortcuts.py", line 24, in render content = loader.render_to_string(template_name, context, request, using=using) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/nix/store/lgnzdwq1kk6lr6wpwz77sa233lkj4hni-python3-3.11.9-env/lib/python3.11/site-packages/django/template/loader.py", line 62, in render_to_string return template.render(context, request) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/nix/store/lgnzdwq1kk6lr6wpwz77sa233lkj4hni-python3-3.11.9-env/lib/python3.11/site-packages/django/template/backends/django.py", line 61, in render return self.template.render(context) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/nix/store/lgnzdwq1kk6lr6wpwz77sa233lkj4hni-python3-3.11.9-env/lib/python3.11/site-packages/django/template/base.py", line 175, in render return self._render(context) ^^^^^^^^^^^^^^^^^^^^^ File "/nix/store/lgnzdwq1kk6lr6wpwz77sa233lkj4hni-python3-3.11.9-env/lib/python3.11/site-packages/django/template/base.py", line 167, in _render return self.nodelist.render(context) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/nix/store/lgnzdwq1kk6lr6wpwz77sa233lkj4hni-python3-3.11.9-env/lib/python3.11/site-packages/django/template/base.py", line 1005, in render return SafeString("".join([node.render_annotated(context) for node in self])) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/nix/store/lgnzdwq1kk6lr6wpwz77sa233lkj4hni-python3-3.11.9-env/lib/python3.11/site-packages/django/template/base.py", line 1005, in <listcomp> return SafeString("".join([node.render_annotated(context) for node in self])) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/nix/store/lgnzdwq1kk6lr6wpwz77sa233lkj4hni-python3-3.11.9-env/lib/python3.11/site-packages/django/template/base.py", line 966, in render_annotated return self.render(context) ^^^^^^^^^^^^^^^^^^^^ File "/nix/store/lgnzdwq1kk6lr6wpwz77sa233lkj4hni-python3-3.11.9-env/lib/python3.11/site-packages/django/template/loader_tags.py", line 157, in render return compiled_parent._render(context) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/nix/store/lgnzdwq1kk6lr6wpwz77sa233lkj4hni-python3-3.11.9-env/lib/python3.11/site-packages/django/template/base.py", line 167, in _render return self.nodelist.render(context) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/nix/store/lgnzdwq1kk6lr6wpwz77sa233lkj4hni-python3-3.11.9-env/lib/python3.11/site-packages/django/template/base.py", line 1005, in render return SafeString("".join([node.render_annotated(context) for node in self])) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/nix/store/lgnzdwq1kk6lr6wpwz77sa233lkj4hni-python3-3.11.9-env/lib/python3.11/site-packages/django/template/base.py", line 1005, in <listcomp> return SafeString("".join([node.render_annotated(context) for node in self])) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/nix/store/lgnzdwq1kk6lr6wpwz77sa233lkj4hni-python3-3.11.9-env/lib/python3.11/site-packages/django/template/base.py", line 966, in render_annotated return self.render(context) ^^^^^^^^^^^^^^^^^^^^ File "/nix/store/lgnzdwq1kk6lr6wpwz77sa233lkj4hni-python3-3.11.9-env/lib/python3.11/site-packages/django/template/loader_tags.py", line 63, in render result = block.nodelist.render(context) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/nix/store/lgnzdwq1kk6lr6wpwz77sa233lkj4hni-python3-3.11.9-env/lib/python3.11/site-packages/django/template/base.py", line 1005, in render return SafeString("".join([node.render_annotated(context) for node in self])) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/nix/store/lgnzdwq1kk6lr6wpwz77sa233lkj4hni-python3-3.11.9-env/lib/python3.11/site-packages/django/template/base.py", line 1005, in <listcomp> return SafeString("".join([node.render_annotated(context) for node in self])) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/nix/store/lgnzdwq1kk6lr6wpwz77sa233lkj4hni-python3-3.11.9-env/lib/python3.11/site-packages/django/template/base.py", line 966, in render_annotated return self.render(context) ^^^^^^^^^^^^^^^^^^^^ File "/nix/store/lgnzdwq1kk6lr6wpwz77sa233lkj4hni-python3-3.11.9-env/lib/python3.11/site-packages/django/template/defaulttags.py", line 321, in render return nodelist.render(context) ^^^^^^^^^^^^^^^^^^^^^^^^ File "/nix/store/lgnzdwq1kk6lr6wpwz77sa233lkj4hni-python3-3.11.9-env/lib/python3.11/site-packages/django/template/base.py", line 1005, in render return SafeString("".join([node.render_annotated(context) for node in self])) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/nix/store/lgnzdwq1kk6lr6wpwz77sa233lkj4hni-python3-3.11.9-env/lib/python3.11/site-packages/django/template/base.py", line 1005, in <listcomp> return SafeString("".join([node.render_annotated(context) for node in self])) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/nix/store/lgnzdwq1kk6lr6wpwz77sa233lkj4hni-python3-3.11.9-env/lib/python3.11/site-packages/django/template/base.py", line 966, in render_annotated return self.render(context) ^^^^^^^^^^^^^^^^^^^^ File "/nix/store/lgnzdwq1kk6lr6wpwz77sa233lkj4hni-python3-3.11.9-env/lib/python3.11/site-packages/django/template/defaulttags.py", line 52, in render output = self.nodelist.render(context) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/nix/store/lgnzdwq1kk6lr6wpwz77sa233lkj4hni-python3-3.11.9-env/lib/python3.11/site-packages/django/template/base.py", line 1005, in render return SafeString("".join([node.render_annotated(context) for node in self])) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ TypeError: sequence item 1: expected str instance, NoneType found ``` A workaround is to empty the `info` field: ``` $ sudo -u mailman mailman withlist -i -l mailman@lists.example.com Welcome to the GNU Mailman shell Use commit() to commit changes. Use abort() to discard changes since the last commit. Exit with ctrl+D does an implicit commit() but exit() does not. The variable 'm' is the mailman@lists.example.com mailing list >>> m.info = '' ```