--- title: [PRE-RFC] PREG_THROW_ON_ERROR flag | daily.dev description: A pre-RFC proposal to the PHP internals mailing list suggests adding a PREG_THROW_ON_ERROR flag to all preg_*() functions. Following the pattern of... canonical: https://daily.dev/posts/pre-rfc-preg-throw-on-error-flag-y0gmmho0a twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: [PRE-RFC] PREG_THROW_ON_ERROR flag | daily.dev og:description: A pre-RFC proposal to the PHP internals mailing list suggests adding a PREG_THROW_ON_ERROR flag to all preg_*() functions. Following the pattern of... og:url: https://daily.dev/posts/pre-rfc-preg-throw-on-error-flag-y0gmmho0a og:image: https://api.daily.dev/og/posts/Y0GMmhO0A.png og:image:alt: [PRE-RFC] PREG_THROW_ON_ERROR flag og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # [PRE-RFC] PREG_THROW_ON_ERROR flag **[externals.io](https://daily.dev/sources/externals)** · 2 min read · 0 upvotes · 0 comments ## Summary A pre-RFC proposal to the PHP internals mailing list suggests adding a PREG_THROW_ON_ERROR flag to all preg_*() functions. Following the pattern of JSON_THROW_ON_ERROR and FILTER_THROW_ON_FAILURE, this flag would make PCRE errors throw a Pcre\PcreException instead of silently returning false or emitting warnings. It would cover both compilation errors (malformed patterns) and execution errors (e.g., bad UTF-8). The proposal also includes adding an optional $flags parameter to preg_replace() and preg_filter(), which currently lack one. Two open design questions are raised: whether to throw on the first failing array element rather than last-one-wins, and whether _ON_ERROR or _ON_FAILURE is the better naming convention. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [\[RFC\] Case sensitive PHP](https://daily.dev/posts/rfc-case-sensitive-php-tglu5yzre) · externals.io · 0 upvotes · 0 comments - [\[RFC\] Deprecations for PHP 8.6](https://daily.dev/posts/rfc-deprecations-for-php-8-6-6rzkdqyuf) · externals.io · 0 upvotes · 0 comments - [\[RFC\] Pattern Matching](https://daily.dev/posts/rfc-pattern-matching-dna1xznxx) · externals.io · 4 upvotes · 0 comments - [\[PRE-RFC\] Deprecate returning from a finally block](https://daily.dev/posts/pre-rfc-deprecate-returning-from-a-finally-block-oiovloynx) · externals.io · 1 upvotes · 0 comments --- Tags: [#php](https://daily.dev/tags/php) [View this post on daily.dev](https://daily.dev/posts/pre-rfc-preg-throw-on-error-flag-y0gmmho0a) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"[PRE-RFC] PREG_THROW_ON_ERROR flag","url":"https://daily.dev/posts/pre-rfc-preg-throw-on-error-flag-y0gmmho0a","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/pre-rfc-preg-throw-on-error-flag-y0gmmho0a"},"datePublished":"2026-07-07T01:28:04.597Z","dateModified":"2026-07-07T01:28:25.642Z","description":"A pre-RFC proposal to the PHP internals mailing list suggests adding a PREG_THROW_ON_ERROR flag to all preg_*() functions. 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