MWException: Default '""' is invalid for preference nickname of user XXX
Closed, ResolvedPublicPRODUCTION ERROR
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Authored By

	• mmodell
	Aug 4 2021, 6:41 PM

Description

Error

mwversion: 1.37.0-wmf.16
reqId: 11842400-6e14-473f-b7ff-173bc0f0f165
Find reqId in Logstash

normalized_message

[{reqId}] {exception_url}   MWException: Default '""' is invalid for preference nickname of user XXX

exception.trace

from /srv/mediawiki/php-1.37.0-wmf.16/includes/preferences/DefaultPreferencesFactory.php(297)
#0 /srv/mediawiki/php-1.37.0-wmf.16/includes/preferences/DefaultPreferencesFactory.php(250): MediaWiki\Preferences\DefaultPreferencesFactory->loadPreferenceValues(User, DerivativeContext, array)
#1 /srv/mediawiki/php-1.37.0-wmf.16/extensions/GlobalPreferences/includes/GlobalPreferencesFactory.php(115): MediaWiki\Preferences\DefaultPreferencesFactory->getFormDescriptor(User, DerivativeContext)
#2 /srv/mediawiki/php-1.37.0-wmf.16/includes/api/ApiOptions.php(207): GlobalPreferences\GlobalPreferencesFactory->getFormDescriptor(User, DerivativeContext)
#3 /srv/mediawiki/php-1.37.0-wmf.16/includes/api/ApiOptions.php(114): ApiOptions->getPreferences()
#4 /srv/mediawiki/php-1.37.0-wmf.16/includes/api/ApiMain.php(1842): ApiOptions->execute()
#5 /srv/mediawiki/php-1.37.0-wmf.16/includes/api/ApiMain.php(821): ApiMain->executeAction()
#6 /srv/mediawiki/php-1.37.0-wmf.16/includes/api/ApiMain.php(792): ApiMain->executeActionWithErrorHandling()
#7 /srv/mediawiki/php-1.37.0-wmf.16/api.php(90): ApiMain->execute()
#8 /srv/mediawiki/php-1.37.0-wmf.16/api.php(45): wfApiMain()
#9 /srv/mediawiki/w/api.php(3): require(string)
#10 {main}

Impact

logspam

Notes

happening for one particular user repeatedly for the past few weeks.

Details

Request URL: https://en.wikipedia.org/w/api.php?format=*&formatversion=*&errorformat=*&errorsuselocal=*&action=options

Related Changes in Gerrit:

	Subject	Repo	Branch	Lines +/-
	Fix exception in preferences when `nickname` is invalid and `fancysig` is on	mediawiki/core	REL1_35	+21 -0
	Fix exception in preferences when `nickname` is invalid and `fancysig` is on	mediawiki/core	master	+11 -8

Customize query in gerrit

Related Objects

Mentioned In: T290195: MWException: Default 'null' is invalid for preference incubatortestwiki-code of user XXX
T281161: 1.37.0-wmf.20 deployment blockers

Event Timeline

• mmodell created this task.Aug 4 2021, 6:41 PM

Restricted Application added a subscriber: Aklapper. · View Herald TranscriptAug 4 2021, 6:41 PM

It seems the preferences code handling has foreseen a scenario where when fancysig is used, a reset causes the empty string value to be used which is then invalid. It tries to handle this scenario in some way to avoid fatals, but maybe that's not working correctly?

Either way, this shoudl not cause an internal server error.

https://gerrit.wikimedia.org/g/mediawiki/core/+/81dd7da45f60ad23bbfe64babd2d9fa4b5e0bce7/includes/preferences/DefaultPreferencesFactory.php#1629

It is called over the api module.

It is possible to get more information about what preference is changed? That are the query parameter change or optionname/optionvalue
Maybe also neccessary to look up the old value for fancysig and nickname.

I have not found a way to trigger the error locally. Maybe ~~~ is in the database or get's set.

thcipriani moved this task from Untriaged to Aug 2021 on the Wikimedia-production-error board.Aug 11 2021, 6:49 PM

This is low-frequency (218 hits in the last 30 days for a particular user) but persistent.

dancy mentioned this in T281161: 1.37.0-wmf.20 deployment blockers.Aug 26 2021, 10:07 PM

The scenario here is that the user's current nickname preference is invalid for some reason, so the code fetching their current preferences tries to replace it with the default value, but the default value is also invalid (because it conflicts with their non-default preference for fancysig).

The real issue is the fact that changing one preference can cause another preference to become invalid. They should be somehow defined differently so that this can't happen. But we probably can't do that without some annoying data migration.

Change 715254 had a related patch set uploaded (by Bartosz Dziewoński; author: Bartosz Dziewoński):

[mediawiki/core@master] Fix exception in preferences when `nickname` is invalid and `fancysig` is on

https://gerrit.wikimedia.org/r/715254

gerritbot added a project: Patch-For-Review.Aug 27 2021, 3:58 PM

Change 715254 merged by jenkins-bot:

[mediawiki/core@master] Fix exception in preferences when `nickname` is invalid and `fancysig` is on

https://gerrit.wikimedia.org/r/715254

Should be fixed in wmf.21.

ReleaseTaggerBot added a project: MW-1.37-notes (1.37.0-wmf.21; 2021-08-30).Aug 27 2021, 8:00 PM

Maintenance_bot removed a project: Patch-For-Review.Aug 27 2021, 8:10 PM

Does the fix also apply to an error like the following:

Default 'null' is invalid for preference incubatortestwiki-code of user <username>

No, it only affects the 'nickname' preference.

dancy mentioned this in T290195: MWException: Default 'null' is invalid for preference incubatortestwiki-code of user XXX.Sep 1 2021, 6:47 PM

Change 834671 had a related patch set uploaded (by Reedy; author: Bartosz Dziewoński):

[mediawiki/core@REL1_35] Fix exception in preferences when `nickname` is invalid and `fancysig` is on

https://gerrit.wikimedia.org/r/834671

Change 834671 abandoned by Reedy: