WC causing preg_match(): null byte in regex in wp-includes\functions.php on line 5163

[indextwo]

EXPLANATION OF THE ISSUE

Running WooCommerce 2.6.13 under WP 2.7.1 or 2.7.2 on XAMPP Apache/PHP7 under Win7, getting error:

preg_match(): null byte in regex in wp-includes\functions.php on line 5163

Getting it on all sites running WooCommerce; stripped down to just WC running with twentyseventeen theme, issue persists. Disable WooCommerce, error disappears.

However, from what I can determine, doesn't seem to be an issue on remote server; nginx running PHP 5.6.

RESULT OF BACKTRACE:

It looks like the core function with the issue is wp_is_stream(). Here's a debug_backtrace of the call stack:

#0  wp_is_stream() called at [C:\xampplite\htdocs\mysite\wp-includes\functions.php:1600]
#1  wp_mkdir_p() called at [C:\xampplite\htdocs\mysite\wp-includes\functions.php:1900]
#2  wp_upload_dir() called at [C:\xampplite\htdocs\mysite\wp-content\plugins\woocommerce\woocommerce.php:178]
#3  WooCommerce->define_constants() called at [C:\xampplite\htdocs\mysite\wp-content\plugins\woocommerce\woocommerce.php:152]
#4  WooCommerce->__construct() called at [C:\xampplite\htdocs\mysite\wp-content\plugins\woocommerce\woocommerce.php:116]
#5  WooCommerce::instance() called at [C:\xampplite\htdocs\mysite\wp-content\plugins\woocommerce\woocommerce.php:551]
#6  WC() called at [C:\xampplite\htdocs\mysite\wp-content\plugins\woocommerce\woocommerce.php:555]
#7  include_once(C:\xampplite\htdocs\mysite\wp-content\plugins\woocommerce\woocommerce.php) called at [C:\xampplite\htdocs\mysite\wp-settings.php:304]
#8  require_once(C:\xampplite\htdocs\mysite\wp-settings.php) called at [C:\xampplite\htdocs\mysite\wp-config.php:142]
#9  require_once(C:\xampplite\htdocs\mysite\wp-config.php) called at [C:\xampplite\htdocs\mysite\wp-load.php:37]
#10 require_once(C:\xampplite\htdocs\mysite\wp-load.php) called at [C:\xampplite\htdocs\mysite\wp-admin\admin.php:31]
#11 require_once(C:\xampplite\htdocs\mysite\wp-admin\admin.php) called at [C:\xampplite\htdocs\mysite\wp-admin\plugins.php:10]

Edit:

having looked into it some more with the information from that call stack, it looks like the issue is directly within the define_constants() function - specifically, if I comment out these two lines:

$upload_dir = wp_upload_dir();
...
$this->define( 'WC_LOG_DIR', $upload_dir['basedir'] . '/wc-logs/' );

...the error disappears.

Edit 2:

I've whittled this down to just the call on wp_upload_dir() - seems to be a core issue. I've submitted a Trac ticket: https://core.trac.wordpress.org/ticket/39722#ticket

SYSTEM STATUS REPORT

### WordPress Environment ###

Home URL: http://localhost/mysite
Site URL: http://localhost/mysite
WC Version: 2.6.13
Log Directory Writable: ?
WP Version: 4.7.2
WP Multisite: –
WP Memory Limit: 1 GB
WP Debug Mode: –
WP Cron: ?
Language: en_GB

### Server Environment ###

Server Info: Apache/2.4.18 (Win32) OpenSSL/1.0.2e PHP/7.0.8
PHP Version: 7.0.8
PHP Post Max Size: 64 MB
PHP Time Limit: 1200
PHP Max Input Vars: 1000
cURL Version: 7.49.1
OpenSSL/1.0.2e

SUHOSIN Installed: –
Max Upload Size: 64 MB
Default Timezone is UTC: ?
fsockopen/cURL: ?
SoapClient: ?
DOMDocument: ?
GZip: ?
Multibyte String: ?
Remote Post: ?
Remote Get: ?

### Database ###

WC Database Version: 2.6.13
: 
woocommerce_sessions: ?
woocommerce_api_keys: ?
woocommerce_attribute_taxonomies: ?
woocommerce_downloadable_product_permissions: ?
woocommerce_order_items: ?
woocommerce_order_itemmeta: ?
woocommerce_tax_rates: ?
woocommerce_tax_rate_locations: ?
woocommerce_shipping_zones: ?
woocommerce_shipping_zone_locations: ?
woocommerce_shipping_zone_methods: ?
woocommerce_payment_tokens: ?
woocommerce_payment_tokenmeta: ?
MaxMind GeoIP Database: ?

### Active Plugins (1) ###

WooCommerce: by WooThemes – 2.6.13

### Settings ###

Force SSL: –
Currency: GBP (£)
Currency Position: left
Thousand Separator: ,
Decimal Separator: .
Number of Decimals: 2

### API ###

API Enabled: ?

### WC Pages ###

Shop Base: #4 - /shop/
Basket: #5 - /basket/
Checkout: #6 - /checkout/
My Account: #7 - /my-account/

### Taxonomies ###

Product Types: external (external)
grouped (grouped)
simple (simple)
variable (variable)


### Theme ###

Name: Twenty Seventeen
Version: 1.1
Author URL: https://wordpress.org/
Child Theme: ? – If you're modifying WooCommerce on a parent theme you didn't build personally
then we recommend using a child theme. See: How to create a child theme

### Templates ###

Overrides: mysite/woocommerce/archive-product.php
mysite/woocommerce/cart\cart-empty.php
mysite/woocommerce/cart\cart-item-data.php
mysite/woocommerce/cart\cart-shipping.php
mysite/woocommerce/cart\cart-totals.php
mysite/woocommerce/cart\cart.php
mysite/woocommerce/cart\cross-sells.php
mysite/woocommerce/cart\mini-cart.php
mysite/woocommerce/cart\proceed-to-checkout-button.php
mysite/woocommerce/checkout\form-billing.php
mysite/woocommerce/checkout\form-checkout.php
mysite/woocommerce/checkout\form-coupon.php
mysite/woocommerce/checkout\form-login.php
mysite/woocommerce/checkout\form-pay.php
mysite/woocommerce/checkout\form-shipping.php
mysite/woocommerce/checkout\payment-method.php
mysite/woocommerce/checkout\payment.php
mysite/woocommerce/checkout\review-order.php
mysite/woocommerce/checkout\terms.php
mysite/woocommerce/checkout\thankyou.php
mysite/woocommerce/content-product.php
mysite/woocommerce/content-single-product.php
mysite/woocommerce/emails\customer-processing-order.php
mysite/woocommerce/emails\email-footer.php
mysite/woocommerce/emails\email-header.php
mysite/woocommerce/emails\email-order-details.php
mysite/woocommerce/emails\email-order-items.php
mysite/woocommerce/emails\email-styles.php
mysite/woocommerce/emails\plain\admin-cancelled-order.php
mysite/woocommerce/emails\plain\admin-failed-order.php
mysite/woocommerce/emails\plain\admin-new-order.php
mysite/woocommerce/emails\plain\customer-completed-order.php
mysite/woocommerce/emails\plain\customer-invoice.php
mysite/woocommerce/emails\plain\customer-new-account.php
mysite/woocommerce/emails\plain\customer-note.php
mysite/woocommerce/emails\plain\customer-processing-order.php
mysite/woocommerce/emails\plain\customer-refunded-order.php
mysite/woocommerce/emails\plain\customer-reset-password.php
mysite/woocommerce/emails\plain\email-addresses.php
mysite/woocommerce/emails\plain\email-customer-details.php
mysite/woocommerce/emails\plain\email-order-details.php
mysite/woocommerce/emails\plain\email-order-items.php
mysite/woocommerce/global\breadcrumb.php
mysite/woocommerce/global\form-login.php
mysite/woocommerce/global\quantity-input.php
mysite/woocommerce/global\sidebar.php
mysite/woocommerce/global\wrapper-end.php
mysite/woocommerce/global\wrapper-start.php
mysite/woocommerce/loop\loop-start.php
mysite/woocommerce/loop\price.php
mysite/woocommerce/loop\sale-flash.php
mysite/woocommerce/myaccount\dashboard.php
mysite/woocommerce/myaccount\form-edit-account.php
mysite/woocommerce/myaccount\form-edit-address.php
mysite/woocommerce/myaccount\form-login.php
mysite/woocommerce/myaccount\form-lost-password.php
mysite/woocommerce/myaccount\form-reset-password.php
mysite/woocommerce/myaccount\lost-password-confirmation.php
mysite/woocommerce/myaccount\my-account.php
mysite/woocommerce/myaccount\my-address.php
mysite/woocommerce/myaccount\my-orders.php
mysite/woocommerce/myaccount\navigation.php
mysite/woocommerce/myaccount\orders.php
mysite/woocommerce/myaccount\view-order.php
mysite/woocommerce/order\form-tracking.php
mysite/woocommerce/order\order-again.php
mysite/woocommerce/order\order-details-customer.php
mysite/woocommerce/order\order-details-item.php
mysite/woocommerce/order\order-details.php
mysite/woocommerce/order\tracking.php
mysite/woocommerce/single-product\add-to-cart\simple.php
mysite/woocommerce/single-product\meta.php
mysite/woocommerce/single-product\price.php
mysite/woocommerce/single-product\product-image.php
mysite/woocommerce/single-product\product-thumbnails.php
mysite/woocommerce/single-product\related.php
mysite/woocommerce/single-product\sale-flash.php
mysite/woocommerce/single-product\share.php
mysite/woocommerce/single-product\short-description.php
mysite/woocommerce/single-product\tabs\tabs.php
mysite/woocommerce/single-product\title.php
mysite/woocommerce/single-product\up-sells.php
mysite/woocommerce/single-product.php
mysite/woocommerce/taxonomy-product_cat.php
mysite/woocommerce/taxonomy-product_tag.php

[indextwo]

I'm closing this, as it's not a WooCommerce issue but one with the core that WC just happens to trigger when it sets its constants. I have found a fix for the issue which currently requires editing a WP core file. Details can be found here:

https://core.trac.wordpress.org/ticket/39722#comment:1