[{reqId}] {exception_url}   PHP Deprecated: Use of $_SESSION was deprecated in MediaWiki 1.27. [Called from session_write_close in (internal function)]

Frame	Location	Call
from	/srv/mediawiki/php-1.44.0-wmf.28/includes/debug/MWDebug.php(386)
#0	[internal function]	MediaWiki\Exception\MWExceptionHandler::handleError(int, string, string, int)
#1	/srv/mediawiki/php-1.44.0-wmf.28/includes/debug/MWDebug.php(386)	trigger_error(string, int)
#2	/srv/mediawiki/php-1.44.0-wmf.28/includes/debug/MWDebug.php(357)	MediaWiki\Debug\MWDebug::sendRawDeprecated(string, bool, string)
#3	/srv/mediawiki/php-1.44.0-wmf.28/includes/debug/MWDebug.php(238)	MediaWiki\Debug\MWDebug::deprecatedMsg(string, string, string, int)
#4	/srv/mediawiki/php-1.44.0-wmf.28/includes/GlobalFunctions.php(782)	MediaWiki\Debug\MWDebug::deprecated(string, string, string, int)
#5	/srv/mediawiki/php-1.44.0-wmf.28/includes/session/PHPSessionHandler.php(327)	wfDeprecated(string, string)
#6	[internal function]	MediaWiki\Session\PHPSessionHandler->write(string, string)
#7	/srv/mediawiki/php-1.44.0-wmf.28/includes/session/SessionManager.php(474)	session_write_close()
#8	[internal function]	MediaWiki\Session\SessionManager->shutdown()
#9	{main}

Notes

I see 2662 in production, all since 1.44.0-wmf.28 (T386223).

Details

Request URL: https://pl.wikipedia.org/w/api.php?action=query&format=*&formatversion=*&meta=*&notfilter=*&notformat=*&notlimit=*&notwikis=*

Related Changes in Gerrit:

	Subject	Repo	Branch	Lines +/-
	Stop logging $wgPHPSessionHandling warnings for now	operations/mediawiki-config	master	+1 -1

Customize query in gerrit

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Status	Subtype	Assigned	Task
Resolved		JTweed-WMF	T398814 WE5.1.1 Session storage protection
Resolved		JTweed-WMF	T400365 Support multiple session stores
Resolved		matmarex	T362324 Disable PHPSessionHandler in Wikimedia production
Resolved	PRODUCTION ERROR	Tgr	T393963 PHP Deprecated: Use of $_SESSION was deprecated in MediaWiki 1.27. [Called from session_write_close in (internal function)]

Event Timeline

brennen created this task.May 12 2025, 8:28 PM

Restricted Application added a subscriber: Aklapper. · View Herald TranscriptMay 12 2025, 8:28 PM

Guessing at some tags here.

(Apparently from this morning's backport window.)

Chould be the result from https://gerrit.wikimedia.org/r/c/operations/mediawiki-config/+/1140725 / T362324

In T362324#10813428, @Tgr wrote:

errors

I think it's bogus, PHPSessionHandler gets confused when the session is dirty on shutdown. The order of things is probably wrong in SessionManager::shutdown().

Can be reverted if the noise is a problem. Otherwise, I'll think about how to prove/disprove with a SessionManager change that this is an incorrect warning.

Tgr added a parent task: T362324: Disable PHPSessionHandler in Wikimedia production.May 12 2025, 8:52 PM

This is now the loudest log in prod. Would it make sense to revert of should we wait for a proper fix?

Umherirrender mentioned this in T394402: Reduce noisy auth logs.May 15 2025, 7:46 PM

Also triggered by one of the integration tests:

1) MediaWiki\Tests\Session\SessionBackendTest::testResetIdOfGlobalSession
Use of $_SESSION was deprecated in MediaWiki 1.27. [Called from session_write_close in (internal function)]

/vagrant/mediawiki/includes/debug/MWDebug.php:386
/vagrant/mediawiki/includes/debug/MWDebug.php:357
/vagrant/mediawiki/includes/debug/MWDebug.php:238
/vagrant/mediawiki/includes/GlobalFunctions.php:782
/vagrant/mediawiki/includes/session/PHPSessionHandler.php:327
/vagrant/mediawiki/includes/session/SessionBackend.php:280
/vagrant/mediawiki/tests/phpunit/includes/session/SessionBackendTest.php:957

Krinkle assigned this task to Tgr.May 19 2025, 2:29 PM

Krinkle moved this task from Inbox, needs triage to In progress (DO NOT USE) on the MediaWiki-Platform-Team board.

sbassett subscribed.May 19 2025, 9:13 PM

Krinkle moved this task from Untriaged to Apr-Jun 2025 on the Wikimedia-production-error board.May 20 2025, 5:38 PM

Umherirrender unsubscribed.May 25 2025, 2:28 PM

brennen moved this task from Backlog to Logs/Train on the User-brennen board.May 28 2025, 11:42 PM

Hello! I'm on train duty this week and this is still the number one error being logged.

In T393963#10813940, @Tgr wrote:

In T362324#10813428, @Tgr wrote:

errors

I think it's bogus, PHPSessionHandler gets confused when the session is dirty on shutdown. The order of things is probably wrong in SessionManager::shutdown().

Can be reverted if the noise is a problem. Otherwise, I'll think about how to prove/disprove with a SessionManager change that this is an incorrect warning.

Do you have the data you need for T362324? Is this still safe to revert? If so, could you revert?

We're still getting about 15 of these warnings a minute on the mediawiki-errors dashboard.

If you've got the data you need for T362324: Disable PHPSessionHandler in Wikimedia production, then removing this message would remove mental overhead for folks assigned to the train each week (as evidenced by all the train conductors commenting here ;))

We haven't found the time to investigate, but we're probably not going to learn anything new by logging these warnings forever. I think it'd be fine to switch them off.

Change #1155303 had a related patch set uploaded (by Bartosz Dziewoński; author: Bartosz Dziewoński):

[operations/mediawiki-config@master] Stop logging $wgPHPSessionHandling warnings for now

https://gerrit.wikimedia.org/r/1155303

gerritbot added a project: Patch-For-Review.Jun 10 2025, 6:13 PM

Change #1155303 merged by jenkins-bot:

[operations/mediawiki-config@master] Stop logging $wgPHPSessionHandling warnings for now

https://gerrit.wikimedia.org/r/1155303

Mentioned in SAL (#wikimedia-operations) [2025-06-11T13:56:58Z] <lucaswerkmeister-wmde@deploy1003> Started scap sync-world: Backport for [[gerrit:1155299|Set $wgPHPSessionHandling to 'disable' on testwiki and beta cluster (T362324)]], [[gerrit:1155303|Stop logging $wgPHPSessionHandling warnings for now (T393963)]]

Mentioned in SAL (#wikimedia-operations) [2025-06-11T13:59:08Z] <lucaswerkmeister-wmde@deploy1003> matmarex, lucaswerkmeister-wmde: Backport for [[gerrit:1155299|Set $wgPHPSessionHandling to 'disable' on testwiki and beta cluster (T362324)]], [[gerrit:1155303|Stop logging $wgPHPSessionHandling warnings for now (T393963)]] synced to the testservers (see https://wikitech.wikimedia.org/wiki/Mwdebug). Changes can now be verified there.

Mentioned in SAL (#wikimedia-operations) [2025-06-11T14:08:12Z] <lucaswerkmeister-wmde@deploy1003> Finished scap sync-world: Backport for [[gerrit:1155299|Set $wgPHPSessionHandling to 'disable' on testwiki and beta cluster (T362324)]], [[gerrit:1155303|Stop logging $wgPHPSessionHandling warnings for now (T393963)]] (duration: 11m 14s)

Maintenance_bot removed a project: Patch-For-Review.Jun 11 2025, 2:30 PM

Thanks!

matmarex closed this task as Resolved.Jun 11 2025, 2:50 PM

Thanks @matmarex <3

matmarex mentioned this in T400668: Debug warnings that were recorded with $wgPHPSessionHandling = 'warn' in WMF production.Jul 29 2025, 2:51 AM

I finally found the time to investigate these warnings, and I think I found the bug and a fix, see T402602. I would like to re-enable these warnings for a day or two before deploying the fix that should resolve (most of) them, to get a baseline for comparison – I hope that won't be a problem, but let me know if I shouldn't do that.

In T393963#11109276, @matmarex wrote:

I would like to re-enable these warnings for a day or two before deploying the fix that should resolve (most of) them, to get a baseline for comparison – I hope that won't be a problem, but let me know if I shouldn't do that.

Sounds fine to me from a security perspective.

In T393963#11109276, @matmarex wrote:

I finally found the time to investigate these warnings, and I think I found the bug and a fix, see T402602. I would like to re-enable these warnings for a day or two before deploying the fix that should resolve (most of) them, to get a baseline for comparison – I hope that won't be a problem, but let me know if I shouldn't do that.

Acknowledging on behalf of Release-Engineering-Team . Making sure @Aklapper knows about this since he's on train duty next.

PHP Deprecated: Use of $_SESSION was deprecated in MediaWiki 1.27. [Called from session_write_close in (internal function)]Closed, ResolvedPublicPRODUCTION ERRORActions

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PHP Deprecated: Use of $_SESSION was deprecated in MediaWiki 1.27. [Called from session_write_close in (internal function)]
Closed, ResolvedPublicPRODUCTION ERROR
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