Portugese language is ok:
https://www.mediawiki.org/wiki/MediaWiki?uselang=pt
https://www.mediawiki.org/wiki/MediaWiki:Mw-manual/pt

Created attachment 15461
Screenshot of a sidebar message

Right. Some sidebar messages seem to have vanished in the space void. For instance mw-download is displayed as empty on wiki and even an old revision which should have 13 bytes lost its text: https://www.mediawiki.org/w/index.php?title=MediaWiki:Mw-download&action=edit&oldid=229289

Attached:

From what I'm seeing, any revisions on mediawiki.org between early 2007 and early 2009 (not sure of the exact dates) have disappeared. This is probably a problem with mediawiki.org's database instead of MediaWiki.

Ex: https://www.mediawiki.org/w/index.php?title=MediaWiki:Mw-extensions&diff=229287&oldid=64636 (One revision of this difference (229287) was not found.)
https://www.mediawiki.org/w/index.php?title=MediaWiki%3ASidebar&diff=231738&oldid=79314 2 revisions of this difference (79314 and 231738) were not found.

Ok, checking 100 rev_id's later gives an example outside ns8. https://www.mediawiki.org/?oldid=229389

Thanks everybody for reporting and investigating here!

1.24wmf6 group 0. From mediawiki.org source code:
<li id="n-mw-bugtracker"><a href="/wiki/Bugzilla"></a></li>
[...]
<li id="n-cat-browser"><a href="INVALID-TITLE"></a></li>
<li id="n-portal"><a href="INVALID-TITLE" title="About the project, what you can do, where to find things">Community portal</a></li>

The example revisions appear intact on the mediawikiwiki database servers (master and slaves), so it might be broken on a higher layer.

Will check external storage and db error logs.

Purged MediaWiki:Support and it reappeared.

That only works on default messages. Purging messages with history only makes the message *name* appear in the menu (revision still not found).

I see the same thing on testwiki, which leads me to suspect an issue in 1.24wmf6.

(In reply to FunPika from comment #3)

From what I'm seeing, any revisions on mediawiki.org between early 2007 and
early 2009 (not sure of the exact dates) have disappeared. This is probably
a problem with mediawiki.org's database instead of MediaWiki.

Probably caused by a7fbdd6503ba, which changed visibility modifiers in includes/HistoryBlob.php, in particular DiffHistoryBlob::$mCompressed.

This sort of problem already appeared twice; see bug 56911 and bug 65375. It has to stop.

(In reply to Kevin Israel (PleaseStand) from comment #10)

Probably caused by a7fbdd6503ba, which changed visibility modifiers in
includes/HistoryBlob.php, in particular DiffHistoryBlob::$mCompressed.

Yes, I just determined that myself. Patch to follow momentarily.

This sort of problem already appeared twice; see bug 56911 and bug 65375. It
has to stop.

Also yes.

Change 135043 had a related patch set uploaded by Anomie:
Revert visibility change on DiffHistoryBlob::$mCompressed

https://gerrit.wikimedia.org/r/135043

Change 135043 merged by jenkins-bot:
Revert visibility change on DiffHistoryBlob::$mCompressed

https://gerrit.wikimedia.org/r/135043

Change 135089 had a related patch set uploaded by Anomie:
Revert visibility change on DiffHistoryBlob::$mCompressed

https://gerrit.wikimedia.org/r/135089

Change 135089 merged by jenkins-bot:
Revert visibility change on DiffHistoryBlob::$mCompressed

https://gerrit.wikimedia.org/r/135089

Fixed and backported. If you see any pages still showing the problem, try purging. If you see any messages not showing up, try going to the MediaWiki-namespace page for the message and purge that (even if it shows up correctly on the page itself). I did this already for the sidebar messages on mediawiki.org.

DiffHistoryBlob::$mCompressed isn't the only bad visibility change in HistoryBlob.php though.

• HistoryBlobStub: $mOldId, $mHash (not sure about $mRef)
• HistoryBlobCurStub: $mCurId

Looks all ok.

(In reply to Kevin Israel (PleaseStand) from comment #17)

DiffHistoryBlob::$mCompressed isn't the only bad visibility change in
HistoryBlob.php though.

• HistoryBlobStub: $mOldId, $mHash (not sure about $mRef)
• HistoryBlobCurStub: $mCurId

Can you file a separate bug to investigate that?

(In reply to Nemo from comment #18)

Can you file a separate bug to investigate that?

It's essentially the same problem and would cause a different set of revisions to be inaccessible.

The diff https://www.mediawiki.org/w/index.php?title=MediaWiki&diff=935&oldid=1 should indicate an increase of 167 bytes. However, "One revision of this difference (935) was not found." and https://www.mediawiki.org/wiki/Special:Redirect/revision/935 gives me a blank page.

Without DB access, I don't know for sure whether that revision's text row has either kind of object, though the revision did end up in the most recent database dump, and there are definitely revisions on other wikis that would be affected (anything that was current at the time of the 1.5 upgrade, plus some more).

Change 135382 had a related patch set uploaded by PleaseStand:
Revert more visibility changes in HistoryBlob.php

https://gerrit.wikimedia.org/r/135382

Change 135382 merged by jenkins-bot:
Revert more visibility changes in HistoryBlob.php

https://gerrit.wikimedia.org/r/135382

Change 135574 had a related patch set uploaded by Anomie:
Revert more visibility changes in HistoryBlob.php

https://gerrit.wikimedia.org/r/135574

Change 135574 merged by jenkins-bot:
Revert more visibility changes in HistoryBlob.php

https://gerrit.wikimedia.org/r/135574

Additional patch merged and backported.