Wikimedia\Assert\PostconditionException: Postcondition failed: Regex failed: 4
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Assigned To

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Authored By

	thcipriani
	Jun 15 2023, 8:11 PM

Description

Error

mwversion: 1.41.0-wmf.13
reqId: a78484f3-32b5-4b95-9f9b-99abd5a87eba
Find reqId in Logstash

normalized_message

[{reqId}] {exception_url}   Wikimedia\Assert\PostconditionException: Postcondition failed: Regex failed: 4

exception.trace

from /srv/mediawiki/php-1.41.0-wmf.13/vendor/wikimedia/assert/src/Assert.php(203)
#0 /srv/mediawiki/php-1.41.0-wmf.13/extensions/CirrusSearch/includes/Parser/QueryStringRegex/NonPhraseParser.php(99): Wikimedia\Assert\Assert::postcondition(boolean, string)
#1 /srv/mediawiki/php-1.41.0-wmf.13/extensions/CirrusSearch/includes/Parser/QueryStringRegex/QueryStringRegexParser.php(693): CirrusSearch\Parser\QueryStringRegex\NonPhraseParser->parse(string, integer, integer)
#2 /srv/mediawiki/php-1.41.0-wmf.13/extensions/CirrusSearch/includes/Parser/QueryStringRegex/QueryStringRegexParser.php(629): CirrusSearch\Parser\QueryStringRegex\QueryStringRegexParser->consumeWord(integer)
#3 /srv/mediawiki/php-1.41.0-wmf.13/extensions/CirrusSearch/includes/Parser/QueryStringRegex/QueryStringRegexParser.php(357): CirrusSearch\Parser\QueryStringRegex\QueryStringRegexParser->nextToken()
#4 /srv/mediawiki/php-1.41.0-wmf.13/extensions/CirrusSearch/includes/Parser/QueryStringRegex/QueryStringRegexParser.php(317): CirrusSearch\Parser\QueryStringRegex\QueryStringRegexParser->expression()
#5 /srv/mediawiki/php-1.41.0-wmf.13/extensions/CirrusSearch/includes/Search/SearchQueryBuilder.php(141): CirrusSearch\Parser\QueryStringRegex\QueryStringRegexParser->parse(string)
#6 /srv/mediawiki/php-1.41.0-wmf.13/extensions/CirrusSearch/includes/CirrusSearch.php(245): CirrusSearch\Search\SearchQueryBuilder::newFTSearchQueryBuilder(CirrusSearch\SearchConfig, string, class@anonymous

Notes

Superficially similar to T334681 stack trace is slightly different
Reproducible via GET request
Volume of errors is much higher obscuring legitimate errors than T334681 if it is unimportant, could we remove the error and return a message to users instead?

Details

Request URL: https://en.wikipedia.org/w/rest.php/v1/search/page?limit=*&q=*

Related Objects

Mentioned In: T340185: The MW Rest API does not normalize its string request parameters
Mentioned Here: T340185: The MW Rest API does not normalize its string request parameters
T334681: Wikimedia\Assert\PostconditionException: Postcondition failed: Regex failed: 4

Event Timeline

thcipriani created this task.Jun 15 2023, 8:11 PM

Restricted Application added a subscriber: Aklapper. · View Herald TranscriptJun 15 2023, 8:11 PM

thcipriani moved this task from Untriaged to Jun 2023 on the Wikimedia-production-error board.Jun 15 2023, 8:11 PM

Gehel moved this task from needs triage to Current work on the Discovery-Search board.Jun 26 2023, 3:27 PM

Gehel edited projects, added Discovery-Search (Current work); removed Discovery-Search.

I think I found the input that causes the problem.

https://en.wikipedia.org/w/rest.php/v1/search/page?limit=20&q=%88

U+0088 = CHARACTER TABULATION SET

So, it's (probably) a weird character that gets parsed oddly somewhere internally and generates an error.

Update: It's not just that one character.. nearby characters are barfing too.

(Also, it's weird that non-regex errors sometimes generate regex error messages)

Wondering if it's not related to the lack of param sanitization/normalization of the REST api (T340185), the same query param does work OK with the opensearch or action API: https://en.wikipedia.org/w/api.php?action=opensearch&limit=10&search=%88

https://en.wikipedia.org/w/api.php?action=query&list=search&srsearch=%88 does warn with The value passed for \"srsearch\" contains invalid or non-normalized data. Textual data should be valid, NFC-normalized Unicode without C0 control characters other than HT (\\t), LF (\\n), and CR (\\r).

moving to blocked/waiting on the Discovery-Search board as I believe this problem is a direct consequence of T340185.

Ping @FJoseph-WMF: we need some kind of intake process for this kind of thing...

Error behavior and cause confirmed. See my comment on T340185 for analysis.

Removing Search Platform, since this is handled at API level

TJones unsubscribed.Aug 7 2023, 4:41 PM

Wikimedia\Assert\PostconditionException: Postcondition failed: Regex failed: 4Open, Needs TriagePublicPRODUCTION ERRORActions