Help:Cite errors/Cite error empty references define

Overview
References may be defined within the reference list:

Note: It is possible to get this error message when nesting footnotes in list-defined references, unfortunately the only fix in this situation is to not use list-defined references for entries that are nested.

Issues and resolution

 * A list-defined reference has no content between the  tags.
 * This error message does not show if reflist is used.
 * Footnotes are nested inside list-defined references. This is a known bug, for now just do not use list-defined references.

Examples
The reference named foo is defined but has no content: