Upgrade fails at this point:

mod_wiki
Adding new fields to wiki table
Renaming old wiki module tables
Installing new wiki module tables
Migrating student type wiki instance: New & Improved
Migrating group type wiki instance: wiki 1
Migrating group type wiki instance: Testing this wiki
Migrating group type wiki instance: Wiki
Migrating group type wiki instance: Presenters Wiki (session details)
Migrating group type wiki instance: Where are you staying - helpful for transport sharing
Migrating student type wiki instance: Reflective Wiki [Do once a week]
Migrating group type wiki instance: Your input
Migrating group type wiki instance: Where are you staying Wiki? ...helpful for transport sharing
Migrating group type wiki instance: Organisers Wiki
Migrating teacher type wiki instance: Workshop Outline
Migrating old wikis to new wikis
Migrating old entries to new subwikis
Migrating old pages to new pages

Error writing to database

More information about this error
Debug info: Duplicate entry '1-New & Improved-0' for key 'mdl_wikipage_subtituse_uix'
INSERT into mdl_wiki_pages (subwikiid, title, cachedcontent, timecreated, timemodified, userid, pageviews)
SELECT s.id, p.pagename, ?, p.created, p.lastmodified, p.userid, p.hits
FROM mdl_wiki_pages_old p
LEFT OUTER JOIN mdl_wiki_entries_old e ON e.id = p.wiki
LEFT OUTER JOIN mdl_wiki_subwikis s
ON s.wikiid = e.wikiid AND s.groupid = e.groupid AND s.userid = e.userid
WHERE p.version = (
SELECT max(po.version)
FROM mdl_wiki_pages_old po
WHERE p.pagename = po.pagename and
p.wiki = po.wiki
)
[array (
0 => '*reparse needed*',
)]
Stack trace:

• line 394 of /lib/dml/moodle_database.php: dml_write_exception thrown
• line 672 of /lib/dml/mysqli_native_moodle_database.php: call to moodle_database->query_end()
• line 187 of /mod/wiki/db/upgrade.php: call to mysqli_native_moodle_database->execute()
• line 490 of /lib/upgradelib.php: call to xmldb_wiki_upgrade()
• line 265 of /lib/upgradelib.php: call to upgrade_plugins_modules()
• line 1352 of /lib/upgradelib.php: call to upgrade_plugins()
• line 290 of /admin/index.php: call to upgrade_noncore()