我正在使用Django-CMS，我创建了一些自定义插件，我在几个页面中使用但在其中一个页面中我无法发布，也无法复制嵌套的插件在这两种情况下都给出了同样的错误：
Internal Server Error: /en/admin/cms/page/copy-plugins/
Traceback (most recent call last):
File "lib\site-packages\django\core\handlers\base.py", line 149, in get_response
response = self.process_exception_by_middleware(e, request)
File "lib\site-packages\django\core\handlers\base.py", line 147, in get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "lib\site-packages\django\utils\decorators.py", line 149, in _wrapped_view
response = view_func(request, *args, **kwargs)
File "lib\site-packages\django\views\decorators\cache.py", line 57, in _wrapped_view_func
response = view_func(request, *args, **kwargs)
File "lib\site-packages\django\contrib\admin\sites.py", line 244, in inner
return view(request, *args, **kwargs)
File "lib\site-packages\django\utils\decorators.py", line 67, in _wrapper
return bound_func(*args, **kwargs)
File "lib\site-packages\django\views\decorators\http.py", line 42, in inner
return func(request, *args, **kwargs)
File "lib\site-packages\django\utils\decorators.py", line 63, in bound_func
return func.__get__(self, type(self))(*args2, **kwargs2)
File "lib\site-packages\django\views\decorators\clickjacking.py", line 39, in wrapped_view
resp = view_func(*args, **kwargs)
File "lib\site-packages\django\utils\decorators.py", line 184, in inner
return func(*args, **kwargs)
File "lib\site-packages\cms\admin\placeholderadmin.py", line 363, in copy_plugins
plugins, target_placeholder, target_language, target_plugin_id)
File "lib\site-packages\cms\utils\copy_plugins.py", line 24, in copy_plugins_to
old_parent_cache, no_signals))
File "lib\site-packages\cms\models\pluginmodel.py", line 319, in copy_plugin
new_plugin.save()
File "lib\site-packages\cms\models\pluginmodel.py", line 240, in save
self.parent.add_child(instance=self)
File "lib\site-packages\treebeard\mp_tree.py", line 970, in add_child
return MP_AddChildHandler(self, **kwargs).process()
File "lib\site-packages\treebeard\mp_tree.py", line 361, in process
newobj.save()
File "lib\site-packages\cms\models\pluginmodel.py", line 248, in save
super(CMSPlugin, self).save(*args, **kwargs)
File "lib\site-packages\django\db\models\base.py", line 708, in save
force_update=force_update, update_fields=update_fields)
File "lib\site-packages\django\db\models\base.py", line 736, in save_base
updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields)
File "lib\site-packages\django\db\models\base.py", line 820, in _save_table
result = self._do_insert(cls._base_manager, using, fields, update_pk, raw)
File "lib\site-packages\django\db\models\base.py", line 859, in _do_insert
using=using, raw=raw)
File "lib\site-packages\django\db\models\manager.py", line 122, in manager_method
return getattr(self.get_queryset(), name)(*args, **kwargs)
File "lib\site-packages\django\db\models\query.py", line 1039, in _insert
return query.get_compiler(using=using).execute_sql(return_id)
File "lib\site-packages\django\db\models\sql\compiler.py", line 1060, in execute_sql
cursor.execute(sql, params)
File "lib\site-packages\django\db\backends\utils.py", line 79, in execute
return super(CursorDebugWrapper, self).execute(sql, params)
File "lib\site-packages\django\db\backends\utils.py", line 64, in execute
return self.cursor.execute(sql, params)
File "lib\site-packages\django\db\backends\mysql\base.py", line 117, in execute
six.reraise(utils.IntegrityError, utils.IntegrityError(*tuple(e.args)), sys.exc_info()[2])
File "lib\site-packages\django\db\backends\mysql\base.py", line 112, in execute
return self.cursor.execute(query, args)
File "build\bdist.win-amd64\egg\MySQLdb\cursors.py", line 205, in execute
self.errorhandler(self, exc, value)
File "build\bdist.win-amd64\egg\MySQLdb\connections.py", line 36, in defaulterrorhandler
raise errorclass, errorvalue
IntegrityError: (1048, "Column 'position' cannot be null")
我已经检查了我的数据库，并且在cms_cmsplugin表中存在一个名为position的列，但没有position null的条目。你知道发生了什么吗？