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Maniphest T221028

Parsoid incorrectly parses links to pages starting with a slash '/' in namespaces that can have subpages
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Description

Parsoid incorrectly parses links to pages starting with a slash '/' in namespaces that can have subpages. Trying to link to (for example) page called "/B" instead generates links to the "B" subpage of the current page.

Transformation is incorrect in both directions:

(assuming page title is User:Matma_Rex/sandbox, tested via https://en.wikipedia.org/api/rest_v1/)

Input<a href=".//B" rel="mw:WikiLink">/B</a>
Actual output[[/B]]
Expected output[[:/B]]
Input[[:/B]]
Actual output<a rel="mw:WikiLink" href="./User:Matma_Rex/sandbox/B" title="User:Matma Rex/sandbox/B" id="mwAw" class="new">/B</a>
Expected output<a rel="mw:WikiLink" href=".//B" title="/B" id="mwAw" class="new">/B</a>

Details

Related Changes in Gerrit:
SubjectAuthorRepoBranchLines +/-
Bump wikimedia/parsoid to 0.24.0-a15Arlolramediawiki/vendorwmf/1.47.0-wmf.11+80 -53
Bump wikimedia/parsoid to 0.24.0-a15OSlegermediawiki/vendormaster+80 -53
Handle slash prefixed links in NSs that allow subpagesJgiannelosmediawiki/services/parsoidmaster+36 -15
Customize query in gerrit

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Event Timeline

• matmarex created this task.Apr 15 2019, 7:29 PM
Restricted Application added a subscriber: Aklapper. · View Herald TranscriptApr 15 2019, 7:29 PM
• matmarex mentioned this in T110413: Relative links to subpages are treated as links to the mainspace that start with / until after saving.Apr 15 2019, 7:32 PM
• matmarex added a parent task: T110413: Relative links to subpages are treated as links to the mainspace that start with / until after saving.
ssastry triaged this task as Medium priority.Apr 15 2019, 8:50 PM
ssastry edited projects, added: Parsoid-Read-Views-Deprecated-Project; removed: Parsoid.
DLynch subscribed.Apr 18 2019, 4:45 PM

I think the suggested behavior here is far less likely to be what people intended than the subpage behavior. Pages whose names start with a / are unusual, and I suspect people are more likely to be trying to link to a subpage.

cscott subscribed.Apr 18 2019, 5:07 PM

As I said over in T110413, .//Foo is pretty dubious as an href. But then again, https://en.wikipedia.org/wiki//e/_(operating_system) exists on enwiki, so I guess that's legit.

https://en.wikipedia.org/wiki/User:Cscott/task221028 shows some of the possibilities.

https://en.wikipedia.org/wiki/Special:ApiSandbox#action=visualeditor&format=json&page=User%3ACscott%2Ftask221028&paction=parse&utf8=1&formatversion=latest seems to confirm that Parsoid is handling the [[: prefix incorrectly.

ssastry moved this task from Uncategorized to Edge cases? on the Parsoid-Read-Views-Deprecated-Project board.Apr 22 2019, 2:14 PM
• matmarex mentioned this in T234299: Links like "[[:/y/]]" and "[[&#x2f;y̫&#x2f;]]" displayed incorrectly in preview.Oct 1 2019, 10:55 PM
Aklapper edited projects, added: Parsoid; removed: Parsoid-Read-Views-Deprecated-Project.Feb 29 2020, 5:14 PM
Arlolra moved this task from Needs Triage to Backlog on the Parsoid board.Mar 2 2020, 3:41 PM
Ostrzyciel subscribed.Nov 5 2020, 4:21 PM

I think this is related to this task: links like [[:/dev/zero]] should point to a page called /dev/zero in the main namespace, not to a subpage of the current page. This is not respected by Parsoid, though, and links like these show up as linking to a subpage.

My testcase: https://en.wikipedia.org/wiki/User:Ostrzyciel/slash_test

Output of the main parser:

image.png (375×86 px, 5 KB)

Appearance in VE when editing:

image.png (549×297 px, 18 KB)

Now this I would consider a serious issue, as there are multiple articles starting with a forward slash on Wikipedia: https://en.wikipedia.org/wiki/Special:PrefixIndex?prefix=%2F&namespace=0&hideredirects=1

Ostrzyciel added a comment.Nov 5 2020, 4:23 PM

Oh, I've just noticed T234299: Links like "[[:/y/]]" and "[[&#x2f;y̫&#x2f;]]" displayed incorrectly in preview... The above comment should have been posted there.

Arlolra moved this task from Backlog to Bugs & Crashers on the Parsoid board.Feb 25 2021, 3:15 PM
Arlolra subscribed.Mar 10 2021, 2:54 PM

T226289 seems to be in the same area and should be solved together

ssastry added a project: Content-Platform-Team.Jun 20 2026, 3:00 AM
ssastry added a project: Parsoid-Read-Views.Jun 20 2026, 3:02 AM
Nardog subscribed.Jun 20 2026, 3:50 AM
Jgiannelos claimed this task.Jun 22 2026, 1:03 PM
Jgiannelos edited projects, added: Content-Platform-Team (Work In Progress); removed: Content-Platform-Team.Jun 22 2026, 3:05 PM
Hakimi97 subscribed.Jun 22 2026, 3:08 PM
ssastry moved this task from Backlog to Q1 FY26-27 on the Content-Platform-Team (Work In Progress) board.Jun 25 2026, 2:49 PM
gerritbot added a comment.Jun 26 2026, 10:17 AM

Change #1305869 had a related patch set uploaded (by Jgiannelos; author: Jgiannelos):

[mediawiki/services/parsoid@master] Handle colon prefixed links in NSs that allow subpages

https://gerrit.wikimedia.org/r/1305869

gerritbot added a project: Patch-For-Review.Jun 26 2026, 10:17 AM
Jgiannelos moved this task from Q1 FY26-27 to Code Review on the Content-Platform-Team (Work In Progress) board.Jul 3 2026, 9:48 AM
MSantos added a project: OKR-Work.Jul 9 2026, 11:33 AM
Jgiannelos moved this task from Code Review to To Deploy on the Content-Platform-Team (Work In Progress) board.Jul 9 2026, 4:40 PM
gerritbot added a comment.Jul 9 2026, 4:47 PM

Change #1305869 merged by jenkins-bot:

[mediawiki/services/parsoid@master] Handle slash prefixed links in NSs that allow subpages

https://gerrit.wikimedia.org/r/1305869

Maintenance_bot removed a project: Patch-For-Review.Jul 9 2026, 5:31 PM
gerritbot added a comment.Jul 13 2026, 6:10 PM

Change #1310144 had a related patch set uploaded (by OSleger; author: OSleger):

[mediawiki/vendor@master] Bump wikimedia/parsoid to 0.24.0-a15

https://gerrit.wikimedia.org/r/1310144

gerritbot added a project: Patch-For-Review.Jul 13 2026, 6:10 PM
gerritbot added a comment.Jul 20 2026, 4:03 PM

Change #1310144 merged by jenkins-bot:

[mediawiki/vendor@master] Bump wikimedia/parsoid to 0.24.0-a15

https://gerrit.wikimedia.org/r/1310144

gerritbot added a comment.Jul 20 2026, 4:19 PM

Change #1312554 had a related patch set uploaded (by Arlolra; author: OSleger):

[mediawiki/vendor@wmf/1.47.0-wmf.11] Bump wikimedia/parsoid to 0.24.0-a15

https://gerrit.wikimedia.org/r/1312554

gerritbot added a comment.Jul 20 2026, 8:16 PM

Change #1312554 merged by jenkins-bot:

[mediawiki/vendor@wmf/1.47.0-wmf.11] Bump wikimedia/parsoid to 0.24.0-a15

https://gerrit.wikimedia.org/r/1312554

Stashbot added a comment.Jul 20 2026, 8:17 PM

Mentioned in SAL (#wikimedia-operations) [2026-07-20T20:17:16Z] <arlolra@deploy2003> Started scap sync-world: Backport for [[gerrit:1312547|Enable PRV on enwiki talk namespace, template namespace]], [[gerrit:1312554|Bump wikimedia/parsoid to 0.24.0-a15 (T221028 T226289 T353697 T430854 T431771)]], [[gerrit:1312556|Bump wikimedia/parsoid to 0.24.0-a15 (T431771)]]

Stashbot mentioned this in T431771: CTT tasks week of 2026-07-10.Jul 20 2026, 8:17 PM
Stashbot mentioned this in T353697: Parsoid/legacy parser {{Pre}} template rendering difference.
Stashbot mentioned this in T430854: Improve handling of image limits by fixing the UX on pages where these limits are hit.
Stashbot mentioned this in T226289: Incorrect href for subpage links in non-subpage-enabled namespaces in Parsoid HTML.
Stashbot added a comment.Jul 20 2026, 8:21 PM

Mentioned in SAL (#wikimedia-operations) [2026-07-20T20:20:59Z] <arlolra@deploy2003> arlolra, cscott: Backport for [[gerrit:1312547|Enable PRV on enwiki talk namespace, template namespace]], [[gerrit:1312554|Bump wikimedia/parsoid to 0.24.0-a15 (T221028 T226289 T353697 T430854 T431771)]], [[gerrit:1312556|Bump wikimedia/parsoid to 0.24.0-a15 (T431771)]] synced to the testservers (see https://wikitech.wikimedia.org/wiki/Mwdebug). Changes can now be verified there.

Maintenance_bot removed a project: Patch-For-Review.Jul 20 2026, 8:31 PM
Stashbot added a comment.Jul 20 2026, 8:32 PM

Mentioned in SAL (#wikimedia-operations) [2026-07-20T20:32:24Z] <arlolra@deploy2003> Finished scap sync-world: Backport for [[gerrit:1312547|Enable PRV on enwiki talk namespace, template namespace]], [[gerrit:1312554|Bump wikimedia/parsoid to 0.24.0-a15 (T221028 T226289 T353697 T430854 T431771)]], [[gerrit:1312556|Bump wikimedia/parsoid to 0.24.0-a15 (T431771)]] (duration: 15m 07s)

ABreault-WMF moved this task from To Deploy to To Verify on the Content-Platform-Team (Work In Progress) board.Jul 20 2026, 8:33 PM
ABreault-WMF closed this task as Resolved.Jul 20 2026, 8:49 PM
ABreault-WMF subscribed.
In T221028#6606476, @Ostrzyciel wrote:

My testcase: https://en.wikipedia.org/wiki/User:Ostrzyciel/slash_test

Post-deploy and purge, the [[:/dev/zero]] is rendered as a blue link on
https://en.wikipedia.org/wiki/User:Ostrzyciel/slash_test?useparsoid=1

From the task description,

curl -X 'POST' \
  'https://en.wikipedia.org/api/rest_v1/transform/wikitext/to/html/User%3AMatma_Rex%2Fsandbox' \
  -H 'accept: text/html; charset=utf-8; profile="https://www.mediawiki.org/wiki/Specs/HTML/2.1.0"' \
  -H 'Content-Type: multipart/form-data' \
  -F 'wikitext=[[:/B]]' \
  -F 'body_only=true' \
  -F 'stash=true'

now yields

<p id="mwAg"><a rel="mw:WikiLink" href=".//B?action=edit&amp;redlink=1" title="/B" class="new" typeof="mw:LocalizedAttrs" id="mwAw" data-mw-i18n='{"title":{"lang":"x-page","key":"red-link-title","params":["/B"]}}'>/B</a></p>

and

curl -X 'POST' \
  'https://en.wikipedia.org/api/rest_v1/transform/html/to/wikitext/User%3AMatma_Rex%2Fsandbox' \
  -H 'accept: text/plain; charset=utf-8; profile="https://www.mediawiki.org/wiki/Specs/wikitext/1.0.0"' \
  -H 'Content-Type: multipart/form-data' \
  -F 'html=<a href='\''.//B'\'' rel='\''mw:WikiLink'\''>/B</a>' \
  -F 'scrub_wikitext=true'

now yields

[[:/B]]
ABreault-WMF merged a task: T423782: Relative links with anchors behave differently in Parsoid vs legacy parser.Thu, Sep 10, 5:19 PM
ABreault-WMF added subscribers: Mr._Starfleet_Command, Herzi.Pinki.
ABreault-WMF mentioned this in T422161: Bug in Parsoid's colon trick handling..Tue, Oct 6, 8:23 PM
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