PHP Notice: Uninitialized string offset: 0
Closed, ResolvedPublicPRODUCTION ERROR
Actions

Description

Error

mwversion: 1.38.0-wmf.20
reqId: 6ef9ceaf-ce7d-48ca-88c2-3e0a6fdedb4f
Find reqId in Logstash

normalized_message

[{reqId}] {exception_url}   PHP Notice: Uninitialized string offset: 0

exception.trace

from /srv/mediawiki/php-1.38.0-wmf.20/includes/cache/MessageCache.php(139)
#0 /srv/mediawiki/php-1.38.0-wmf.20/includes/cache/MessageCache.php(139): MWExceptionHandler::handleError(integer, string, string, integer, array)
#1 /srv/mediawiki/php-1.38.0-wmf.20/includes/api/ApiQueryAllMessages.php(182): MessageCache::normalizeKey(string)
#2 /srv/mediawiki/php-1.38.0-wmf.20/includes/api/ApiQuery.php(629): ApiQueryAllMessages->execute()
#3 /srv/mediawiki/php-1.38.0-wmf.20/includes/api/ApiMain.php(1890): ApiQuery->execute()
#4 /srv/mediawiki/php-1.38.0-wmf.20/includes/api/ApiMain.php(868): ApiMain->executeAction()
#5 /srv/mediawiki/php-1.38.0-wmf.20/includes/api/ApiMain.php(839): ApiMain->executeActionWithErrorHandling()
#6 /srv/mediawiki/php-1.38.0-wmf.20/api.php(90): ApiMain->execute()
#7 /srv/mediawiki/php-1.38.0-wmf.20/api.php(45): wfApiMain()
#8 /srv/mediawiki/w/api.php(3): require(string)
#9 {main}

And this associated one

normalized_message

[{reqId}] {exception_url}   PHP Warning: Cannot assign an empty string to a string offset

exception.trace

from /srv/mediawiki/php-1.38.0-wmf.20/includes/cache/MessageCache.php(139)
#0 /srv/mediawiki/php-1.38.0-wmf.20/includes/cache/MessageCache.php(139): MWExceptionHandler::handleError(integer, string, string, integer, array)
#1 /srv/mediawiki/php-1.38.0-wmf.20/includes/api/ApiQueryAllMessages.php(182): MessageCache::normalizeKey(string)
#2 /srv/mediawiki/php-1.38.0-wmf.20/includes/api/ApiQuery.php(629): ApiQueryAllMessages->execute()
#3 /srv/mediawiki/php-1.38.0-wmf.20/includes/api/ApiMain.php(1890): ApiQuery->execute()
#4 /srv/mediawiki/php-1.38.0-wmf.20/includes/api/ApiMain.php(868): ApiMain->executeAction()
#5 /srv/mediawiki/php-1.38.0-wmf.20/includes/api/ApiMain.php(839): ApiMain->executeActionWithErrorHandling()
#6 /srv/mediawiki/php-1.38.0-wmf.20/api.php(90): ApiMain->execute()
#7 /srv/mediawiki/php-1.38.0-wmf.20/api.php(45): wfApiMain()
#8 /srv/mediawiki/w/api.php(3): require(string)
#9 {main}

Notes

A small burst of these appeared in logs. I haven't seen this before.

Details

MediaWiki Version: 1.38.0-wmf.20
Request URL: https://ar.wiktionary.org/w/api.php?action=query&meta=*&ammessages=*&amlang=*&amnocontent=*

	Subject	Repo	Branch	Lines +/-
	MessageCache: Avoid Undefined offset in normalizeKey()	mediawiki/core	master	+5 -0

Customize query in gerrit

Event Timeline

dancy created this task.Feb 2 2022, 9:28 PM

Restricted Application added a subscriber: Aklapper. · View Herald TranscriptFeb 2 2022, 9:28 PM

dancy updated the task description. (Show Details)Feb 2 2022, 9:31 PM

Reedy added a project: MediaWiki-Action-API.Feb 3 2022, 1:30 AM

Krinkle moved this task from Untriaged to Feb 2022 on the Wikimedia-production-error board.Feb 4 2022, 3:27 AM

MessageCache::normalizeKey applies a strtolower operation to the first character of its string parameter, which emits this error when given an empty string.

MessageCache itself avoids this by not calling it with empty strings. ApiQueryAllMessages calls this seemingly-internal method directly on user input, hence fails.

While the empty string cannot exist as a message, it is considered a valid interface message key by all localisation-related classes that I checked, it simply results in boolean false the same as for other message keys that don't exist. The Action API allows empty string in its multi-value parameters, and omitting it from the result would create a confusing situation.

Hence, I think the call from ApiQueryAllMessages is actually reasonable, so maybe normalizeKey should be fixed instead?

Change 759641 had a related patch set uploaded (by Krinkle; author: Krinkle):

[mediawiki/core@master] MessageCache: Avoid Undefined offset in normalizeKey()

https://gerrit.wikimedia.org/r/759641

gerritbot added a project: Patch-For-Review.Feb 4 2022, 3:41 AM

Krinkle claimed this task.Feb 4 2022, 3:41 AM

Krinkle triaged this task as Low priority.Feb 4 2022, 4:18 AM

Krinkle added a project: Performance-Team.

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

Change 759641 merged by jenkins-bot:

[mediawiki/core@master] MessageCache: Avoid Undefined offset in normalizeKey()

https://gerrit.wikimedia.org/r/759641