TypeError: Cannot read properties of null (reading 'toLowerCase') at at mw.language.getData
Closed, ResolvedPublicPRODUCTION ERROR
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Assigned To

Authored By

	Jdlrobson
	Feb 9 2023, 8:56 PM

Description

Occurring inside https://codesearch.wmcloud.org/search/?q=getSeparatorTransformTable&i=nope&files=&excludeFiles=&repos=
In last 7 days error occurred 1,018 times.

Error

mwversion: undefined
reqId: undefined
https://logstash.wikimedia.org/goto/217414a13f32aa269a477559f5abcaa9

normalized_message

TypeError: Cannot read properties of null (reading 'toLowerCase')

at Object.getData  <anonymous>:380:1241
at Object.getSeparatorTransformTable  <anonymous>:387:462
at Object.convertNumber  <anonymous>:386:438
at Object.getLastModifiedMessage  <anonymous>:287:722
at initHistoryLink  <anonymous>:182:714
at HTMLSpanElement.<anonymous>  <anonymous>:183:475
at Function.each  https://es.m.wikipedia.org/w/load.php?lang=es&modules=ext.discussionTools.init%7Cjquery%2Cmoment%2Coojs-ui-core&skin=minerva&version=56atz:307:285
at jQuery.fn.init.each  https://es.m.wikipedia.org/w/load.php?lang=es&modules=ext.discussionTools.init%7Cjquery%2Cmoment%2Coojs-ui-core&skin=minerva&version=56atz:305:93
at initModifiedInfo  <anonymous>:183:459
at HTMLDocument.<anonymous>  <anonymous>:184:675

Impact

Last modified message on mobile rendering incorrectly.

Notes

Details

	Subject	Repo	Branch	Lines +/-
	ResourceLoader: Permit partial failure in OutputPage::getBottomScripts	mediawiki/core	master	+2 -1
	ResourceLoader: Permit partial failure of encodeJson() and add logging	mediawiki/core	master	+33 -1

Customize query in gerrit

Related Objects

Mentioned In: T331641: Context::encodeJson partially failed (invalid modules parameter)
T328037: Exception: JSON serialization of config data failed. (via OutputPage::getBottomScripts)
Mentioned Here: T32956: Make ResourceLoader a standalone library
T206475: Users are unable to edit (add new topics to) [[:fa:wikipedia:پرسش‌های متفرقه]]
T207876: Fatal error from ResourceLoader: JSON serialization of config data failed (due to wgInternalRedirectTargetUrl)
T208689: Fatal error: JSON serialization of config data failed, invalid UTF-8 (via Scribunto)
T328037: Exception: JSON serialization of config data failed. (via OutputPage::getBottomScripts)
rMWcd45307ba162: resourceloader: Move per-page function calls to startup.js

Event Timeline

Jdlrobson created this task.Feb 9 2023, 8:56 PM

Restricted Application added subscribers: Masumrezarock100, Aklapper. · View Herald TranscriptFeb 9 2023, 8:56 PM

This is an issue with mediawiki.language but I'm not sure what the appropriate tag is.
The Mobilefrontend call triggering this looks pretty harmless - it's either 0 or 1:
https://gerrit.wikimedia.org/g/mediawiki/extensions/MobileFrontend/+/8c3a95825084f26e8bacaf36a4022357d03303b2/src/mobile.startup/time.js#110

It seems mw.config.get( 'wgUserLanguage' ) returns null for some reason in these cases. It gets passed to getData which then fails in langCode = langCode.toLowerCase();.

Since this doesn't seem to be related to languages per se, I am untagging Language-Team per our maintenance levels.

Umherirrender added a project: JavaScript.Feb 10 2023, 6:25 PM

wgUserLanguage is added via includes/ResourceLoader/ResourceLoader.php.

Looking closely most of the errors came from a single client (anonymous) but there are 4 different users impacted by the error, so perhaps this should be declined, but might also point to some kind of cache poisoning (I've not thought too much about that)?.

Restricted Application added a project: Performance-Team. · View Herald TranscriptFeb 13 2023, 5:48 PM

Krinkle claimed this task.Feb 13 2023, 8:07 PM

Krinkle triaged this task as High priority.

Krinkle moved this task from Inbox, needs triage to Doing: Goals on the Performance-Team board.

Krinkle moved this task from Doing: Goals to Doing: Prio Interrupt on the Performance-Team board.Feb 13 2023, 8:10 PM

This is most likely due to an extension adding a key-value pair to mw.config with a string that is not valid UTF-8. This means it can't be encoded as JSON, and thus fails the blob.

This task currently lacks any detail to know what URL it is failing on what extensions may be active for a given combination of (wiki, user account, page title) and by extent skin/language preferences.

This seems to come up once or twice a year, with usually a dedicated task for specific breakages once identified, such as:

core mw.config wgInternalRedirectTargetUrl: T207876: Fatal error from ResourceLoader: JSON serialization of config data failed (due to wgInternalRedirectTargetUrl)
Scribunto mw.config data: T208689: Fatal error: JSON serialization of config data failed, invalid UTF-8 (via Scribunto)
Flow mw.config data: T206475: Users are unable to edit (add new topics to) [[:fa:wikipedia:پرسش‌های متفرقه]]

As part of T206475, we decided to make this category of issue more visible by adding a fatal error instead of continuing to render the page without mw.config. As per T328037, this logic is still working and incurring a fatal error. However, the issue in this task did not receive a fatal error because the invalid data encountered here is part of the RLCONF payload in the <head> which we format with Context->encodeJson() rather than the old static ResourceLoader::makeConfigSetScript. The former was introduced for T32956, and adopted in https://gerrit.wikimedia.org/r/503705 (cd45307ba16230) to improve performance.

Given that this task has not yet identified which extension broke it, I'll focus this task on fixing the detection in RL and thus the side-effect observed by mw.language.getData. There will then later be a separate task for the root cause, which as per the above, is likely an extension adding invalid data.

Krinkle mentioned this in T328037: Exception: JSON serialization of config data failed. (via OutputPage::getBottomScripts).Feb 14 2023, 11:25 PM

Change 889256 had a related patch set uploaded (by Krinkle; author: Krinkle):

[mediawiki/core@master] ResourceLoader: Permit partial failure of encodeJson() and add logging

https://gerrit.wikimedia.org/r/889256

gerritbot added a project: Patch-For-Review.Feb 14 2023, 11:40 PM

Change 889258 had a related patch set uploaded (by Krinkle; author: Krinkle):

[mediawiki/core@master] ResourceLoader: Permit partial failure in OutputPage::getBottomScripts

https://gerrit.wikimedia.org/r/889258

Jdlrobson awarded a token.Feb 15 2023, 12:24 AM

Change 889256 merged by jenkins-bot:

[mediawiki/core@master] ResourceLoader: Permit partial failure of encodeJson() and add logging

https://gerrit.wikimedia.org/r/889256

ReleaseTaggerBot added a project: MW-1.40-notes (1.40.0-wmf.24; 2023-02-20).Feb 16 2023, 1:00 AM

Change 889258 merged by jenkins-bot: