Images missing in Android and iOS applications
Closed, ResolvedPublicBUG REPORT
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Authored By

	TheDJ
	Apr 17 2023, 9:00 AM

Description

Steps to replicate the issue (include links if applicable):

iOS app and/or Android app
Users report that the first image in the article is present but subsequent images are missing and only their caption is shown.
Reports on wiki and on Discord
Was able to reproduce, but not sure if it reproduces consistently

What happens?:
No image is shown

What should have happened instead?:
Image should be shown

Software version (skip for WMF-hosted wikis like Wikipedia):

Other information (browser name/version, screenshots, etc.):

Related Objects

Mentioned In: T328943: Replace PCS lazy-loading logic with standard "loading=lazy" attribute
T336251: Introduce versioning in PCS output and static assets
Mentioned Here: T328943: Replace PCS lazy-loading logic with standard "loading=lazy" attribute

Event Timeline

TheDJ created this task.Apr 17 2023, 9:00 AM

Restricted Application added a subscriber: Aklapper. · View Herald TranscriptApr 17 2023, 9:00 AM

ARamadan-WMF subscribed.Apr 17 2023, 9:47 AM

Dbrant triaged this task as High priority.Apr 17 2023, 11:03 AM

Dbrant added a project: Content-Transform-Team.

Jgiannelos claimed this task.Apr 17 2023, 11:14 AM

I think the problem is because of inconsistency in the output between the pregenerated content on the restbase level and the JS we serve from PCS.
More specifically for this broken page on PCS:

This page is pregenerated and stored from storage on restbase: https://en.wikipedia.org/api/rest_v1/page/mobile-html/Cat
The page loads the PCS JS from: https://meta.wikimedia.org/api/rest_v1/data/javascript/mobile/pcs
The latest PCS JS is using lazy loading introduced here: https://phabricator.wikimedia.org/T328943
The pregenerated page is stuck in an older state and the lazy loading doesn't work
Purging the page forces a re-render and eventually brings the page to the right state

Here is an example:
The working HTML for a given image is:

<span>
 <a href="./File:Cat_August_2010-4.jpg" class="mw-file-description">
  <img alt="" resource="./File:Cat_August_2010-4.jpg" src="//upload.wikimedia.org/wikipedia/commons/thumb/1/15/Cat_August_2010-4.jpg/181px-Cat_August_2010-4.jpg" decoding="async" data-file-width="3640" data-file-height="2226" data-file-type="bitmap" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/15/Cat_August_2010-4.jpg/272px-Cat_August_2010-4.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/15/Cat_August_2010-4.jpg/362px-Cat_August_2010-4.jpg 2x" loading="lazy" width="181" height="111">
 </a>
</span>

And the broken state for the same image:

<span>
 <a href="./File:Cat_August_2010-4.jpg" class="mw-file-description">
  <span class="pcs-lazy-load-placeholder pcs-lazy-load-placeholder-pending" style="width: 181px;" data-src="//upload.wikimedia.org/wikipedia/commons/thumb/1/15/Cat_August_2010-4.jpg/181px-Cat_August_2010-4.jpg" data-srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/15/Cat_August_2010-4.jpg/272px-Cat_August_2010-4.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/15/Cat_August_2010-4.jpg/362px-Cat_August_2010-4.jpg 2x" data-width="181" data-height="111" data-alt="" data-data-file-width="3640" data-data-file-height="2226">
   <span style="padding-top: 61.32596685082873%;">
   </span>
  </span>
 </a>
</span>

Dbrant merged a task: T334844: pictures not displaying on french version mobile application.Apr 17 2023, 1:15 PM

Dbrant added a subscriber: Batouki.

We deployed mobileapps after reverting this: https://gerrit.wikimedia.org/r/c/mediawiki/services/mobileapps/+/908961
Also forced invalidation of PCS JS on restbase level and purged the meta.wikimedia.org edge endpoint for PCS JS.

The last problem which is unavoidable is the client side caching:

http --headers https://meta.wikimedia.org/api/rest_v1/data/javascript/mobile/pcs
cache-control: public, max-age=86400, s-maxage=86400

I took a look to a few pages that had broken images and now they work fine.

Jgiannelos added a project: Content-Transform-Team-WIP.Apr 17 2023, 1:26 PM

Jgiannelos moved this task from Backlog to To Verify on the Content-Transform-Team-WIP board.

Okay does this mean the problem is fixed? @Jgiannelos

JTannerWMF added a subscriber: Seddon.Apr 17 2023, 2:20 PM

Update not to reflect any new issue but to reflect the seriousness

From the environments I have access to reproduce the issue it looks fixed. I am not entirely sure for cases were the problematic JS is cached in the client side were we should wait for it to expire.

The users' reports on this bug can be found in this sheet.

Closing this one since even client side caches should have expired by now.

Jgiannelos closed this task as Resolved.Apr 18 2023, 1:42 PM

Jgiannelos mentioned this in T336251: Introduce versioning in PCS output and static assets.May 9 2023, 11:31 AM

TheDJ mentioned this in T328943: Replace PCS lazy-loading logic with standard "loading=lazy" attribute.Nov 21 2023, 4:02 PM

Images missing in Android and iOS applicationsClosed, ResolvedPublicBUG REPORTActions

Description

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Event Timeline

Images missing in Android and iOS applications
Closed, ResolvedPublicBUG REPORT
Actions