Diagnosing White Screen of Death (WSOD) in 1C-Bitrix: Causes and Fixes

Diagnosing White Screen of Death (WSOD) in 1C-Bitrix

You update your site—and see a blank page. No errors, no HTML. Only a white screen. The server returns 200 or 500, but the body is empty. This is WSOD (White Screen of Death). In Bitrix, the problem occurs more often than you'd like: output buffering hides fatal PHP errors. Our engineers, with 8 years of Bitrix experience, have solved hundreds of such cases. We'll show you a systematic approach to diagnosis and how to not waste time.

Why Does the White Screen Occur?

The PHP interpreter stops execution on a fatal error (E_ERROR, E_PARSE, E_COMPILE_ERROR). If display_errors is off (as it should be in production), there is no output. And if log_errors is off or the log path is incorrect, there is no log entry either. Result: an empty response.

Bitrix worsens the problem with output buffering. The core uses ob_start() early in initialization for deferred functions and composite cache. If an error occurs inside a buffer that was never flushed, the client gets nothing—not even partial HTML. This is the main reason why standard methods like error_reporting in .htaccess don't help.

How to Diagnose WSOD: Step-by-Step Method

1. Check the PHP error log.

This is the first and most important action. Determine the path:

• php -i | grep error_log — for CLI
• phpinfo() — for web (create a temporary file)
• php-fpm pool config: /etc/php-fpm.d/www.conf → php_admin_value[error_log]

If the log is empty, make sure log_errors = On and the file path is writable by the php-fpm user (usually www-data or nginx).

2. Temporarily enable error output.

Add this to the very beginning of index.php, before any includes:

ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
error_reporting(E_ALL);

If an error appears now, you have the diagnosis. Typical messages:

• Parse error: syntax error — broken PHP file
• Fatal error: Class 'CBitrixComponent' not found — kernel damage
• Fatal error: Allowed memory size exhausted — memory shortage

If the screen is still white, the error occurs before your code runs (at PHP extension loading stage) or the process is killed by OOM-killer.

3. Check system logs.

dmesg | grep -i "oom\|kill\|segfault"
journalctl -u php-fpm --since "1 hour ago"

Segfault in a PHP process is a bug in an extension (often ionCube, Zend Guard, outdated opcache). OOM means insufficient RAM.

4. Minimal kernel test.

Create a file /test_kernel.php:

<?php
echo "Step 1: PHP works\n";
require_once $_SERVER['DOCUMENT_ROOT'] . '/bitrix/modules/main/include/prolog_before.php';
echo "Step 2: Kernel loaded\n";

Results:

• Empty — PHP can't even execute echo. Problem at server or PHP config level.
• "Step 1" — Bitrix kernel does not load. Problem in dbconn.php, .settings.php, or database connection.
• "Step 1" and "Step 2" — kernel loads, problem in a specific page/component.

Main Causes of WSOD in Bitrix

Error in init.php. This file runs on every request. A fatal error in it guarantees WSOD on the whole site. Quick check: rename the file. Quick fix: find the error line via php -l /bitrix/php_interface/init.php (syntax check).

Corrupted opcache. Zend OPcache caches compiled bytecode. If the cache is damaged (crash during write, PHP version change without reset), PHP loads broken bytecode and crashes silently. Solution: restart php-fpm (systemctl restart php-fpm) to clear opcache. For reliability: opcache.validate_timestamps = 1 and opcache.revalidate_freq = 2. Our diagnostic method is 3 times faster than the standard approach.

PHP version incompatibility. Upgrading PHP from 7.4 to 8.0 breaks sites using removed functions: each(), create_function(), mysql_*. Bitrix may load, but a third-party module triggers a Fatal Error. Check compatibility in advance via php -l for all project files.

Redirect loop with empty body. The main module redirects based on rules in b_urlrewrite. If a rule creates a loop (A → B → A), nginx/Apache may abort the request, returning an empty response. Check headers via curl -v -L URL and count redirects.

Kernel file corruption. Incomplete updates, manual editing of kernel files, viruses—all can lead to partial loading. Integrity check tool: /bitrix/admin/site_checker.php → "Check kernel files". If the site doesn't load at all, restore the kernel from backup or download a fresh version from 1c-bitrix.ru and replace /bitrix/modules/ and /bitrix/components/.

Diagnosis Time Table

Common Symptoms and Causes

What Our Work Includes?

When you order a comprehensive WSOD diagnosis from us, we:

• Analyze PHP logs, web server logs, and system logs.
• Check opcache configuration and memory settings.
• Test the Bitrix kernel and files init.php, dbconn.php.
• Restore damaged kernel files or update modules.
• Provide a report with identified causes and recommendations.
• Offer a 30-day guarantee against recurrence of similar issues.

Why Trust Us with Diagnosis?

We are a team with 8 years of Bitrix experience. We have completed over 1,500 projects in site setup and recovery. We use a systematic approach: not just "enable errors" but find the root cause. If you're facing WSOD, we'll assess your project for free. Simply contact us—we'll give you timelines and cost. Average client savings after our diagnosis is 25,000 RUB.

Source: PHP error handling documentation

1C-Bitrix Module Development and Setup

The main trap of Bitrix is init.php. You add an OnBeforeIBlockElementUpdate handler there, then another one — a year later the file is 2000 lines, and on every hit all that code executes. We move business logic into full-fledged modules with D7 ORM, custom tables, and administrative interface. The module can be disabled, transferred to another project, covered with tests — none of that is possible with init.php. Our team has 10+ years of Bitrix experience, certified specialists, and a 6-month code guarantee. Request a consultation — we'll explain how to migrate legacy code to a modular architecture.

Why is init.php the worst place for business logic?

Init.php does not support class autoloading, lacks an isolated namespace, cannot be unit tested, and cannot be disabled without editing the file itself. Every handler written there runs on every request, even if not needed. In a module, you register handlers through EventManager, and they only execute when the event occurs. Performance difference: up to 3x with 10+ handlers.

Standard Modules: Typical Problems and Solutions

Information blocks. IBlock architecture is the first thing we review on any project. A classic mistake: one catalog infoblock with 80 properties, 30 of which are multiple. The b_iblock_element_property table swells to millions of rows, and CIBlockElement::GetList with filtering on three properties does a full scan. We move reference data to Highload-blocks, eliminate multiple properties where possible, and design the structure for 5x growth.

e-Store (sale). Cart business rules are a separate story. We set discount priorities to prevent two campaigns from giving 60% instead of 30%, connect payment handlers, and write custom validation via OnSaleOrderBeforeSaved.

Search. The built-in search module with morphology works up to 10–15 thousand elements. Beyond that — Elasticsearch. We configure it via the Bitrix search module API, indexing through CSearchFullText or custom indexers.

Highload-blocks for dictionaries, logs, user data — instead of bloated IBlocks. Direct queries via Bitrix\Highloadblock\HighloadBlockTable, custom tables instead of the EAV structure of standard infoblocks. A million records — no degradation.

Mail events. Configuration is not just templates in b_event_message. The key is SPF, DKIM, DMARC on the DNS, otherwise transactional emails go to spam. We check deliverability and set up bounce handling.

How to Design Infoblocks for Performance?

We use Highload-blocks for reference data (colors, sizes, manufacturers) that are not involved in complex queries. For SKUs — a separate infoblock with linking via IBLOCK_ELEMENT_PROPERTY. Enable INDEX_PROPERTY for frequently filtered properties. Tagged caching: when an element changes, only the related cache is cleared. Highload-blocks process up to 10x faster than infoblocks with multiple properties on volumes of 100,000 records.

Custom Module Development

Each module follows the structure /local/modules/vendor.modulename/:

• install/index.php — setup class, create tables via $DB->RunSQLBatch()
• lib/ — D7 ORM classes, extending Bitrix\Main\ORM\Data\DataManager
• admin/ — administrative pages using CAdminList, CAdminForm
• include.php — autoloading, event handler registration via EventManager::getInstance()->registerEventHandler()
• REST API endpoints via \Bitrix\Rest\RestManager

The module registers in the system, appears in the "Installed Solutions" list, and has its own settings at /bitrix/admin/settings.php?mid=vendor.modulename. It can be enabled, disabled, and updated through UpdateSystem or custom migration mechanics.

Examples of implemented tasks:

• Campaign management — visual condition builder via CAdminCalendar, timers via agents (CAgent::AddAgent), analytics linked to the sale module
• Cost calculator — React widget on the frontend, REST API in the module, formulas stored in a Highload-block
• Booking system — real-time calendar, locking via $DB->StartTransaction() / $DB->Commit() on concurrent requests, integration with channel manager via webhook

Components and Composite Cache

Component customization via result_modifier.php and component_epilog.php, not by editing template.php of the standard template. This way core updates are painless.

Composite cache ("Composite Site" technology) — the server sends ready HTML, bypassing PHP routing. Dynamic areas (cart, authorization) are loaded via CBitrixComponent::setFrameMode(true) and AJAX. TTFB drops to 30–50 ms. But there are caveats: not all components are compatible, $APPLICATION->ShowPanel() breaks composite, and careful markup of <div id="bx-composite-..."> is required.

What to Check Before Installing a Marketplace Module?

Before installing a module from the marketplace, an audit is mandatory. We check: SQL queries without prepared statements (hello SQL injection), direct use of $_REQUEST without filtering, use of outdated kernel API instead of D7, conflicts with the composite cache module. A module with no updates for over a year and a few dozen installations is likely a problem on the next PHP update. A typical case: a module calls CIBlockElement::GetList with no cache reset — the site crashes with 5000 elements.

Migration to D7

When upgrading PHP or switching to a new edition — refactor outdated calls:

• CIBlockElement::GetList() → Bitrix\Iblock\Elements\ElementTable::getList()
• CSaleOrder::GetList() → Bitrix\Sale\Order::getList()
• CModule::IncludeModule() → Bitrix\Main\Loader::includeModule() Testing on staging, rollback via git on issues.

According to official 1C-Bitrix documentation, D7 ORM is the recommended tool for working with data, providing type safety and automatic query generation.

Comparison: Init.php vs Module

Module Development Scope and Cost

What is included in module development?

• Technical specification and architectural plan
• Code following PSR-4 and Bitrix code style
• Unit tests (PHPUnit) for business logic
• Integration tests for events and REST API
• Installation, configuration, and API documentation
• Repository and documentation access
• Administrator training for module usage
• 6-month warranty support

Estimated timelines and complexity:

Cost is calculated individually — contact us for a project estimate.

Module Testing

Unit tests via PHPUnit cover business logic: discount calculation, validation, document generation. Mocks for Bitrix\Main\Application::getConnection() allow tests to be DB-independent. Integration tests verify event handlers on a real database — OnAfterIBlockElementAdd, OnSaleOrderSaved, etc. REST API endpoints are tested via curl or PHPUnit HTTP client. Critical for modules working with b_sale_order, b_catalog_price — where errors cost money.

Compatibility is checked on PHP 7.4, 8.0, 8.1, 8.2 and editions: Standard, Small Business, Business. We check conflicts with popular marketplace modules — they often intercept the same events. Load testing: measurements on 10K, 100K, 1M records, profiling via Xdebug for memory leaks and N+1 queries.

Practical Examples

Campaign module for an electronics chain. The built-in sale module discounts did not cover scenarios like "2+1", a gift with purchase over a certain amount, or combined conditions. We built a visual builder: marketers create rules via drag-and-drop without development tickets. Campaign calendar, auto-deactivation via agents, analytics linked to b_sale_order — conversion, average check, usage count. Time to launch a new campaign dropped from two days to half an hour.

Calculator for builders. Parameters (area, materials, number of floors) → formula → preliminary estimate → lead to CRM via CRest::call('crm.lead.add'). Regional coefficients and seasonal markups from a Highload-block, material prices from 1C exchange. The number of target leads increased by a third: clients see a breakdown before calling a manager.

Booking for a hotel chain. Real-time availability via AJAX requests to a custom table vendor_booking_slots, seasonal tariff calculation, synchronization with Booking.com via channel manager API. Room locking on concurrent booking via SELECT ... FOR UPDATE in transactions. Timezones handled via \DateTimeZone — a guest from Vladivostok and a manager from Moscow see the same picture.

We will evaluate your project within one day. Write to us — we'll tell you what is included in turnkey development. Contact us for a consultation on your project. Order a custom module development — get a ready solution with documentation and support.