Which mobile app do you use ? Android or iPhone ? Is present on both ? What app / os version ?

I have this problem on Android 7.1.1 with the official app - version 2.5.195-r-2017-04-21.

Note: the number of displays has clearly increased in recent days, but it remains acceptable
https://fr.wikipedia.org/w/index.php?title=Aide:Documentation_de_mod%C3%A8le&action=info

This should be the same on Android and iOS. Looks like the page https://fr.wikipedia.org/wiki/MediaWiki:Ffeed-featured-page doesn't resolve to the correct featured article page.
The contents are currently

Modèle:Lumière sur/Aujourd'hui

An earlier version of

Wikipédia:Lumière sur/{{ucfirst:{{CURRENTMONTHNAME}} {{CURRENTYEAR}}}}

should actually work. I don't know why that change has been made. To change it back it would require someone with UI editor rights, as discussed in T148680.

If you know someone with that permission please let me know. The alternative is to remove French from the list of supported languages for the featured article in the Explore feed.

(Trizek is sysop on frwiki :)

In T166577#3306264, @bearND wrote:

This should be the same on Android and iOS. Looks like the page https://fr.wikipedia.org/wiki/MediaWiki:Ffeed-featured-page doesn't resolve to the correct featured article page.
The contents are currently

Modèle:Lumière sur/Aujourd'hui

An earlier version of

Wikipédia:Lumière sur/{{ucfirst:{{CURRENTMONTHNAME}} {{CURRENTYEAR}}}}

should actually work. I don't know why that change has been made. To change it back it would require someone with UI editor rights, as discussed in T148680.

If you know someone with that permission please let me know. The alternative is to remove French from the list of supported languages for the featured article in the Explore feed.

Change done.

But why a page last updated on 26 January 2012‎ causes trouble now...

Hi, I still have the same problem now, I think it just moves the place of the "Featured Article", which is [[Aide:Documentation de Modèle]]. Now, I have the "Picture of the day" in first place, (and I think it wasn't like that before, but maybe I'm wrong).

Android 6.0 - Xperia XA - Application : 2.5.195-r-2017-04-21

Well, good luck ^^

On my phone, I have [[Aide:Documentation de Modèle]] in the section for May 31st, and nothing for June 1st. Android 7.0, 2.5.195-beta-2017-04-21.
On my tablet, I have the same thing. Android 4.4.2, 2.5.195-r-2017-04-21

@Trizek-WMF Thank you for making the change. Now it does pick up the correct intermediary page.

Yes, currently it doesn't pick up the featured article because it's looking for the first bolded link inside the first paragraph (<p>). On this page the first paragraph contains guidelines under the "Principe" heading. I can make some code changes to the service to help pick up the link to the featured article title. Until that is deployed it would show no featured article. That's still better than having it point to the help page.

In T166577#3307232, @GrandCelinien wrote:

Hi, I still have the same problem now, I think it just moves the place of the "Featured Article", which is [[Aide:Documentation de Modèle]]. Now, I have the "Picture of the day" in first place, (and I think it wasn't like that before, but maybe I'm wrong).

For today it doesn't show any featured article, so the app skips the featured article for today and the picture of the day card is next. Then at some point it goes to the previous day. It will still show the help page for the featured article on the previous days due to caching.
Later today I will look into clearing the caches in RESTBase for the French feed content of at least the last month. Ideally I'll get this merged and deployed today then I only have to do the cache purge once.

Change 356621 had a related patch set uploaded (by BearND; owner: BearND):
[mediawiki/services/mobileapps@master] TFA: less restrictive search for featured article

https://gerrit.wikimedia.org/r/356621

@bearND, have you considered to have a format, like a class for a span HTML block, that will ease your research of content on the wikis? Somethong like <span class="mw-features-article-abstract"> ...</span>
That would ease your life a lot, and I'm sure communities would be happy to use it. :)

@Trizek-WMF , yes we actually have. @Fjalapeno has written up a document about this.

So the problem is that https://fr.wikipedia.org/wiki/Mod%C3%A8le:Lumi%C3%A8re_sur/Accueil transcludes {{Palette Lumière sur}} {{Lumière sur/Accueil/Introduction}} outside the template namespace?

For now I suggest to change the overly smart ifexpr at the beginning of https://fr.wikipedia.org/w/index.php?title=Mod%C3%A8le:Lumi%C3%A8re_sur/Accueil&action=edit to something like {{#ifeq:{{NAMESPACENUMBER}}|10|{{Palette Lumière sur}} {{Lumière sur/Accueil/Introduction}}|}}

I have no idea what {{FULLPAGENAME}}, {{NAMESPACE}}, {{PAGENAME}}, {{BASEPAGENAME}} evaluate to in api.php?action=featuredfeed .

Change 356621 merged by jenkins-bot:
[mediawiki/services/mobileapps@master] TFA: less restrictive search for featured article

https://gerrit.wikimedia.org/r/356621

In T166577#3308952, @Nemo_bis wrote:

I have no idea what {{FULLPAGENAME}}, {{NAMESPACE}}, {{PAGENAME}}, {{BASEPAGENAME}} evaluate to in api.php?action=featuredfeed .

Whatever the name of the page is (e.g. Wikipédia:Lumière sur/Juin 2017).

In T166577#3309091, @Tgr wrote:

Whatever the name of the page is (e.g. Wikipédia:Lumière sur/Juin 2017).

So that's the problem, the template should be changed to not output the overlong navigational stuff and instructions in the Wikipedia namespace (or in the current month's page).

Just linking this to the Hungarian ticket so we can track these issues

The featured article of the day is now back on the home page. If there is anything to change on fr.wp to have more stability, please ask.

In T166577#3308132, @bearND wrote:

@Trizek-WMF , yes we actually have. @Fjalapeno has written up a document about this.

Thanks, I'll have a look at it.