KeyError: 'constrainTypesMode'

Here is an excerpt of error I run into:

URL: plone/app/layout/viewlets/contentactions.pt
Line 32, Column 8
Expression: <StringExpr u'plone.contentmenu'>
...
URL: plone/app/contentmenu/contentmenu.pt
Line 1, Column 0
Expression: <PathExpr standard:u'view/menu'>
...
KeyError: 'constrainTypesMode'

It turns out from my typo in content/mytype.py, by the time when I hesitate whether if using a folderish type:

-ArticleSchema = folder.ATContentTypeSchema.copy()
+ArticleSchema = folder.ATFolderSchema.copy()