Related to the actor migration? Pinging @Anomie.

In T207288#4674488, @Jdforrester-WMF wrote:

Related to the actor migration? Pinging @Anomie.

Seems unlikely at first glance.

I put mediawikiwiki onto wmf.26 on mwdebug1002 for testing and could not reproduce the issue. I also can't reproduce it locally.

Regarding the pasted trace, I find that both the data in the getKnownCurrentRevision() cache and the data it would fetch from the database look valid (and in particular do have rev_user and rev_user_text set), for both the top revision of [[mw:MediaWiki:Sidebar]] and the revision previous.

Further, the warning listed seems unlikely to result in the sidebar messages going missing.

Oh, that stack trace is probably bogus. My local vagrant instance is messed up, as the issue only pops up when literally visiting MediaWiki:Sidebar. I've intermittently had problems with the actor migration process for a while now. I'm sorry for putting everyone on a false track here.

Mentioned in SAL (#wikimedia-operations) [2018-10-17T19:23:06Z] <twentyafterfour> Mediawiki train is still blocked by T207288

@Anomie: does this need to be closed as invalid?

The stack trace I've provided is not relevant to this issue, but please do check https://www.mediawiki.org/wiki/MediaWiki, and observe that the sidebar still doesn't show the expected text.

In T207288#4675362, @Mainframe98 wrote:

The stack trace I've provided is not relevant to this issue, but please do check https://www.mediawiki.org/wiki/MediaWiki, and observe that the sidebar still doesn't show the expected text.

... If it's happening for you now even though we're rolled back to wmf.24, does this actually need to block the train?

@Mainframe98: I'm not seeing what you mean? The sidebar looks normal for me.

I can only reproduce this on a few devices, I suspect whatever it is, is slowly disappearing with wmf.24. If you think it is safe to proceed, please do so.

In T207288#4675362, @Mainframe98 wrote:

please do check https://www.mediawiki.org/wiki/MediaWiki, and observe that the sidebar still doesn't show the expected text.

I cannot reproduce this problem.
@Mainframe98: Do you also see the problem when using a private browser window? Have you already tried bypassing your browser cache? Does this also happen with another browser? Which browser(s) did you try this with? Are you logged in or logged out on mediawiki.org?

This is really strange. So when in Incognito mode, the expected sidebar shows. When logging off, the expected sidebar shows. When logging back on, the sidebar with the incorrect messages is shown again. It's not a script either, using ?safemode=1 has the same issue.

I can reproduce this across three devices, and it absolutely baffles me. Is there any cache that somehow only affects logged-in users?

@Aklapper I've done some investigating in the comment above. Additionally, the same behaviour occurs in Microsoft Edge, Internet Explorer 11 and Google Chrome (70). Also on Google Chrome on an iPad, and Android Phone, all latest versions of them.

Hmm. I see it when visiting https://www.mediawiki.org/wiki/Special:Version?uselang=nl. Checking caches, I see that the cached sidebar for language nl does have those incorrect texts.

When I execute the code that would be run when the cache entry expires it generates a correct sidebar, even on wmf.26.

@Anomie: how can we clear the cache?

It appears that everything has returned to normal again. For me at least, as visiting the main page in Italian: https://www.mediawiki.org/wiki/MediaWiki?uselang=it, still shows the incorrect version. I can only imagine that there are incorrect versions for other languages.

In T207288#4676017, @mmodell wrote:

@Anomie: how can we clear the cache?

From mwrepl, something like this should do it:

$languageCode = 'nl'; // Or whatever other language
$wanCache = MediaWiki\MediaWikiServices::getInstance()->getMainWANObjectCache();
$wanCache->delete( $wanCache->makeKey( 'sidebar', $languageCode ) );

I'm still not sure if this is a real blocker or just a spurious issue. I deployed wmf.26 to group0 last night and I'd like to get the train moving again if possible but I don't want to move forward with a bug that's going to break translations everywhere.