In T184912#3919272, @David_J_Wilson wrote:

In T184912#3900555, @Aklapper wrote:

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(This task welcomes editing its task description to make it clearer by providing sections for: Description of the problem; expected behavior; actual behavior. See https://mediawiki.org/wiki/How_to_report_a_bug for future reference.)

Description: A reference name containing a double underscore produces an inline link which does not work. The back-link from the footnote to the text does not work either.

Example: (from https://en.wikipedia.org/wiki/Help_talk:Footnotes#Double_underscores_in_footnote_names )

Footnote constructor: <ref name="garlic__bread">Here is an example</ref>

Anchor produced at footnote: <li id="cite_note-garlic__bread-1">, as expected
Anchor produced at reference superscript is also as expected. I can't quote it because another double underscore will screw up the text displayed. However, apart from a double underscore between "garlic" and "bread" instead of one, its name is the same as that of the back link given below.

Link to footnote produced: <a href="cite_note-garlic_bread-1"> with only one underscore between "garlic" and "bread" instead of the expected two.
Back link produced: <a href="cite_ref-garlic_bread_1-0"> ditto

Cause: The link and anchor names don't match because the former erroneously have only one underscore between "garlic" and "bread" instead of the expected two.

In T184912#3900555, @Aklapper wrote:

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(This task welcomes editing its task description to make it clearer by providing sections for: Description of the problem; expected behavior; actual behavior. See https://mediawiki.org/wiki/How_to_report_a_bug for future reference.)