Editing Template:Hatnote/doc (section)

==Errors==
If no Hatnote text is supplied, the template will output the following message:
* {{Hatnote|category=no}}

If you see this error message, it is for one of four reasons:
# No parameters were specified (the template code was {{T|Hatnote}}). Please use {{T|Hatnote|''text''}} instead.
# Some parameters were specified, but the Hatnote text wasn't included. For example, the template text {{T|Hatnote|extraclasses=seealso}} will produce this error. Please use (for example) {{T|Hatnote|''text''|extraclasses=seealso}} instead.
# The Hatnote text was specified, but that text contains an equals sign ("="). The equals sign has a special meaning in template code, and because of this it cannot be used in template parameters that do not specify a parameter name. For example, the template code {{T|Hatnote|2+2{{=}}4}} will produce this error. To work around this, you can specify the parameter name explicitly by using {{F|1=}} before the Hatnote text, like this: {{T|Hatnote|p1=1=2+2=4}}
# You tried to access [[Module:Hatnote]] directly by using {{F|<nowiki>{{#invoke:Hatnote|Hatnote|''text''}}</nowiki>}} Use of #invoke in this way has been disabled for performance reasons. Please use {{T|Hatnote|''text''}} instead.

Pages that contain this error message are tracked in [[:Category:Hatnote templates with errors]].