This may have been fixed for the new articles, but I spotted this ones created on 2015-06-29.

Soft hyphens in titles are bad. I remove them regularly. Blocking or at least creating a warning would be useful.

On the other hand soft hyphens are useful for titles with very long words. With T66528 I suggest to allow to insert soft hyphens into the display title.

Change 393381 had a related patch set uploaded (by Fomafix; owner: Fomafix):
[mediawiki/core@master] [WIP] Strip soft hyphens (U 00AD) from title

https://gerrit.wikimedia.org/r/393381

On enwiki there are currently the following titles containing soft hyphens. They are all redirects:

1. https://en.wikipedia.org/wiki/Baltimore­Washington_Parkway?redirect=no
2. https://en.wikipedia.org/wiki/Comprehensive_Environmental_Response,_Compen­sation,_and_Liability_Act?redirect=no
3. https://en.wikipedia.org/wiki/Comprehensive_Environmental_Response,_Compen­sation,_and_Liability_Act_of_1980?redirect=no
4. https://en.wikipedia.org/wiki/Immuni­sation?redirect=no
5. https://en.wikipedia.org/wiki/India­-Myanmar_relations?redirect=no
6. https://en.wikipedia.org/wiki/Kendall,_Tay­lor_&_Com­pany?redirect=no
7. https://en.wikipedia.org/wiki/Kendall,_Tay­lor_and_Com­pany?redirect=no
8. https://en.wikipedia.org/wiki/Lopado­temacho­selacho­galeo­kranio­leipsano­drim­hypo­trimmato­silphio­parao?redirect=no
9. https://en.wikipedia.org/wiki/Lopado­temacho­selacho­galeo­kranio­leipsano­drim­hypo­trimmato­silphio­parao­melito­katakechy­meno­kichl­epi­kossypho­phatto­perister­alektryon­opte­kephallio­kigklo­peleio­lagoio­siraio­baphe­tragano­pterygon?redirect=no
10. https://en.wikipedia.org/wiki/Whip­lash_Shaken_Infant_Syndrome?redirect=no
11. https://en.wikipedia.org/wiki/­?redirect=no
12. https://en.wikipedia.org/wiki/Œu­v­re?redirect=no

After deploying https://gerrit.wikimedia.org/r/393381 these titles are invalid and get renamed by maintenance/cleanupTitles.php. The redirects can already deleted before deploying because they are superfluously because it exists an article or a redirect with a title without soft hyphens.

There are actually 30 such titles on enwiki, when you count other namespaces. Some are usernames, which makes this a bit awkward, but luckily it seems they are all permanently banned, so while we'll probably need to do something special about them, we won't annoy anyone when they are renamed.

I am currently running this query for this across all wikis to see what we should expect.

select
  page_namespace, page_title, page_is_redirect, replace(a.page_title,'­','') as page_title_new,
  (select count(*) from page b where b.page_namespace=a.page_namespace and b.page_title=page_title_new) as conflicts
from page a where page_title like '%­%'

Results for all Wikimedia wikis. page_title_new columns has the title with the soft hyphen removed, and conflicts column indicates whether a page with the "fixed" title already exists on the wiki.

There are 2322 such pages across all our wikis, including 913 on kuwiktionary and the rest spread across 153 other wikis.

798 of these have no conflicts and we could just rename to the version without a hyphen.

1275 are redirects with conflicts. Most of these are probably redirects to the soft-hyphen-less title, but we can't check that with just a SQL query.

249 are non-redirects that have a title conflict. Users will have to deal with these manually.

Change 393381 merged by jenkins-bot:
[mediawiki/core@master] Strip soft hyphens (U+00AD) from title

https://gerrit.wikimedia.org/r/393381

Change 493162 had a related patch set uploaded (by Fomafix; owner: Fomafix):
[mediawiki/core@master] Strip characters from title

https://gerrit.wikimedia.org/r/493162

Change 493162 had a related patch set uploaded (by Fomafix; owner: Fomafix):
[mediawiki/core@master] Strip characters from title

https://gerrit.wikimedia.org/r/493162

Change 582468 had a related patch set uploaded (by Fomafix; owner: Fomafix):
[mediawiki/services/parsoid@master] Strip additional special Unicode characters from title

https://gerrit.wikimedia.org/r/582468