Broken Link Checker Installation Failed

Hi, we’re having trouble installing BLC on our Production site. It installs and runs fine on our Dev environment but not Production or Preprod.

All environments are hosted on WP VIP using PHP 8.1, WordPress 6.6.1 and a custom theme.

Upon trying to install, the following is shown in the WP dashboard:

Broken Link Checker installation failed. Try deactivating and then reactivating the plugin.
installation_complete = 0
installation_flag_cleared_on = 2023-11-10T16:41:24+00:00 (1699634484.3933)
installation_flag_set_on = 0

Installation log follows :
Plugin activated at 2023-11-10 09:40:07.
Installation/update begins.
Upgrading the database...
... SHOW TABLES (0.002 seconds)
... SHOW FULL COLUMNS FROM wp_blc_filters 0.001 seconds
... SHOW INDEX FROM wp_blc_filters 0.001 seconds
... SHOW FULL COLUMNS FROM wp_blc_instances 0.001 seconds
... SHOW INDEX FROM wp_blc_instances 0.001 seconds
... SHOW FULL COLUMNS FROM wp_blc_links 0.001 seconds
... SHOW INDEX FROM wp_blc_links 0.001 seconds
... SHOW FULL COLUMNS FROM wp_blc_synch 0.001 seconds
... SHOW INDEX FROM wp_blc_synch 0.001 seconds
[OK] ALTER TABLE wp_blc_filters MODIFY COLUMN id int(10) unsigned NOT NULL AUTO_INCREMENT (0.006 seconds)
[OK] ALTER TABLE wp_blc_instances MODIFY COLUMN instance_id int(10) unsigned NOT NULL AUTO_INCREMENT (0.004 seconds)
[OK] ALTER TABLE wp_blc_instances MODIFY COLUMN link_id int(10) unsigned NOT NULL (0.009 seconds)
[OK] ALTER TABLE wp_blc_instances MODIFY COLUMN container_id int(10) unsigned NOT NULL (0.006 seconds)
[OK] ALTER TABLE wp_blc_instances MODIFY COLUMN link_text text NOT NULL DEFAULT '' (0.011 seconds)
[OK] ALTER TABLE wp_blc_links MODIFY COLUMN link_id int(20) unsigned NOT NULL AUTO_INCREMENT (0.008 seconds)
[OK] ALTER TABLE wp_blc_links MODIFY COLUMN check_count int(4) unsigned NOT NULL DEFAULT '0' (0.011 seconds)
[OK] ALTER TABLE wp_blc_links MODIFY COLUMN redirect_count smallint(5) unsigned NOT NULL DEFAULT '0' (0.015 seconds)
[OK] ALTER TABLE wp_blc_links MODIFY COLUMN http_code smallint(6) NOT NULL DEFAULT '0' (0.021 seconds)
[OK] ALTER TABLE wp_blc_links MODIFY COLUMN timeout tinyint(1) unsigned NOT NULL DEFAULT '0' (0.016 seconds)
[OK] ALTER TABLE wp_blc_links MODIFY COLUMN broken tinyint(1) unsigned NOT NULL DEFAULT '0' (0.017 seconds)
[OK] ALTER TABLE wp_blc_links MODIFY COLUMN warning tinyint(1) unsigned NOT NULL DEFAULT '0' (0.015 seconds)
[OK] ALTER TABLE wp_blc_synch MODIFY COLUMN container_id int(20) unsigned NOT NULL (45.438 seconds)
[OK] ALTER TABLE wp_blc_synch MODIFY COLUMN synched tinyint(2) unsigned NOT NULL (20.756 seconds)
Schema update took 66.344 seconds
Database schema updated.
Database successfully upgraded.
--- Total: 66.519 seconds
Cleaning up the database...
... Deleting invalid container records
... 0 synch records deleted in 0.001 seconds
... Deleting invalid link instances
... 0 instances deleted in 0.000 seconds
... 0 more instances deleted in 0.000 seconds
... Deleting orphaned links
... 0 links deleted in 0.000 seconds
--- Total: 0.002 seconds
Notifying modules...
... Updating module cache
... Cache refresh took 0.193 seconds
... Loading modules
... 4 modules loaded in 0.002 seconds
... Notifying module "http"
... Notifying module "link"
... Notifying module "image"
... Notifying module "metadata"
... Notifying module "url_field"
... Notifying module "comment"
...... Deleting synch. records for removed comments
...... 0 rows deleted in 3.872 seconds
...... Creating synch. records for new comments
...... 0 rows inserted in 20.866 seconds
... Notifying module "acf"
... Notifying module "post"
...... Deleting synch records for removed posts & post with invalid status
DELETE synch.* FROM wp_blc_synch AS synch WHERE synch.container_id NOT IN ('11250200', '11251495', '11250700', '11250538', '11249586', '11248797', '11248567', '11248262', '11247817', '11247366', '11246816', '11246339', '11246007', '11245080', '11244276', '11243809', '11243520', '11242681', '11242112', '11241567', '11241289', '11241068', '11240971', '11240222', '11239635', '11238971', '11238251', '11237717', '11237145', '11236724',

The only related error we can find in the error logs is:

PHP message: PHP Fatal error: Uncaught Error: Class "blcUtility" not found in /var/www/wp-content/plugins/broken-link-checker/legacy/core/core.php:1723

If Site Health info helps you, here it is:

<br>### wp-core ###<br><br>version: 6.6.1<br>site_language: en_US<br>user_language: en_US<br>timezone: America/Boise<br>permalink: /%year%/%monthnum%/%day%/%postname%/<br>https_status: true<br>multisite: true<br>user_registration: false<br>blog_public: 1<br>default_comment_status: open<br>environment_type: production<br>site_id: 1<br>site_count: 4<br>network_count: 1<br>user_count: 304801<br>dotorg_communication: true<br><br>### wp-dropins (3) ###<br><br>db.php: true<br>object-cache.php: true<br>sunrise.php: true<br><br>### wp-active-theme ###<br><br>name: Redacted (redacted)<br>version: 1.0.0<br>author: Redacted<br>author_website: https://redacted.com<br>parent_theme: none<br>theme_features: core-block-patterns, widgets-block-editor, block-templates, infinite-scroll, menus, automatic-feed-links, title-tag, post-thumbnails, html5, custom-background, customize-selective-refresh-widgets, custom-logo, wp-block-styles, align-wide, editor-styles, responsive-embeds, appearance-tools, border, widgets, editor-style<br>theme_path: /var/www/wp-content/themes/redacted<br><br>### wp-mu-plugins (38) ###<br><br>Admin Notice: version: 0.1.0, author: WordPress VIP<br>Advanced Post Caching: version: 0.2, author: Automattic<br>Akismet Anti-Spam: version: 5.1, author: Automattic<br>blogpublic-notice.php: author: (undefined), version: (undefined)<br>HTTP Concat: version: 1.0, author: Automattic<br>Jetpack: version: 13.7, author: Automattic<br>Lightweight Term Count Update: version: 0.1.0, author: Automattic, Alley Interactive<br>prometheus.php: author: (undefined), version: (undefined)<br>query-monitor.php: author: (undefined), version: (undefined)<br>REST API Enhancements: version: 0.1, author: Erick Hitter, Automattic<br>Rewrite Rules Inspector: version: 1.4.0, author: Automattic, Daniel Bachhuber<br>VaultPress: version: 2.2.1, author: Automattic<br>VIP AllOptions Safeguard: author: Automattic, version: (undefined)<br>VIP Back-compat: version: 1.0, author: Automattic<br>VIP Cache Manager: version: 1.1, author: Automattic<br>VIP Client mu-plugins: author: Automattic, version: (undefined)<br>VIP Codebase Manager: version: 1.0.0, author: Automattic<br>VIP Cron Enhancements: version: 1.0, author: Automattic<br>VIP Dashboard: version: 3.0.0, author: Scott Evans, Filipe Varela, Pau Argelaguet<br>VIP Feed Cache: author: Automattic, version: (undefined)<br>VIP File Service: version: 0.2, author: Automattic<br>VIP Force Two Factor: author: Automattic, version: (undefined)<br>VIP Go Core Modifications: author: Automattic, version: (undefined)<br>VIP Go Plugin Compat: version: 1.0, author: Automattic<br>VIP Hosting Miscellaneous: version: 1.1, author: Automattic<br>VIP Init: author: Automattic, version: (undefined)<br>VIP Integrations: author: Automattic, version: (undefined)<br>VIP Mail: version: 1.0, author: Automattic<br>VIP Parse.ly Integration: version: 1.0, author: Automattic<br>VIP Performance: version: 1.0, author: Automattic<br>VIP Plugins: version: 1.0.0, author: Automattic<br>VIP Schema: author: Automattic, version: (undefined)<br>VIP Security: version: 1.2, author: Automattic<br>VIP Stats: author: Automattic, version: (undefined)<br>WooCommerce: VIP Specific Changes: version: 1.0.0, author: Automattic<br>WordPress Importer: version: 0.6.4, author: wordpressdotorg<br>WordPress VIP Support: version: 3.1.0, author: <a href="https://automattic.com">Automattic</a><br>WP-CLI for VIP Go: author: Automattic, version: (undefined)<br><br>### wp-plugins-active (16) ###<br><br>Ads.txt Manager: version: 1.4.4, author: 10up<br>Advanced Custom Fields PRO: version: 6.3.5, author: WP Engine (latest version: 6.3.6)<br>Block Admin Emails: version: 1.0.0, author: Redacted<br>Bulk Delete: version: 6.0.2, author: Sudar<br>Cache Nav Menus: version: 1.0, author: Automattic<br>Comment Reply Email Notification: version: 1.33.0, author: Arno Welzel<br>External Links in a New Window: version: 1.0, author: Javi Moya<br>Fieldmanager: version: 1.2.4, author: Alley<br>Gravity Forms: version: 2.8.16, author: Gravity Forms (latest version: 2.8.17)<br>IndexNow: version: 1.0.3, author: Microsoft Bing<br>Sticky Custom Post Types: version: 1.2.3, author: Ann Oyama<br>Term Management Tools: version: 2.0.1, author: theMikeD, scribu<br>TK Favorites: version: 1.0.0, author: Redacted<br>WP Post Publish AYS: version: 0.1.0, author: John James Jacoby<br>Yoast SEO: version: 23.2, author: Team Yoast (latest version: 23.4)<br>Yoast SEO Premium: version: 23.2, author: Team Yoast<br><br>### wp-plugins-inactive (1) ###<br><br>Yoast Test Helper: version: 1.18, author: Team Yoast<br><br>### wp-media ###<br><br>image_editor: WP_Image_Editor_GD<br>imagick_module_version: Not available<br>imagemagick_version: Not available<br>imagick_version: Not available<br>file_uploads: 1<br>post_max_size: 2047M<br>upload_max_filesize: 2047M<br>max_effective_size: 2 GB<br>max_file_uploads: 20<br>gd_version: bundled (2.1.0 compatible)<br>gd_formats: GIF, JPEG, PNG, WebP, BMP, AVIF<br>ghostscript_version: not available<br><br>### wp-server ###<br><br>server_architecture: Linux 5.10.0-26-amd64 x86_64<br>httpd_software: nginx<br>php_version: 8.2.22 64bit<br>php_sapi: fpm-fcgi<br>max_input_variables: 6144<br>time_limit: 1200<br>memory_limit: 768M<br>max_input_time: 1200<br>upload_max_filesize: 2047M<br>php_post_max_size: 2047M<br>curl_version: 8.7.1 OpenSSL/1.1.1w<br>suhosin: false<br>imagick_availability: false<br>pretty_permalinks: true<br>current: 2024-09-04T08:31:50+00:00<br>utc-time: Wednesday, 04-Sep-24 08:31:50 UTC<br>server-time: 2024-09-04T02:31:50-06:00<br><br>### wp-database ###<br><br>extension: mysqli<br>server_version: 8.0.28<br>client_version: mysqlnd 8.2.22<br>max_allowed_packet: 67108864<br>max_connections: 400<br><br>### wp-constants ###<br><br>WP_HOME: undefined<br>WP_SITEURL: undefined<br>WP_CONTENT_DIR: /var/www/wp-content<br>WP_PLUGIN_DIR: /var/www/wp-content/plugins<br>WP_MEMORY_LIMIT: 64M<br>WP_MAX_MEMORY_LIMIT: 512M<br>WP_DEBUG: false<br>WP_DEBUG_DISPLAY: false<br>WP_DEBUG_LOG: false<br>SCRIPT_DEBUG: false<br>WP_CACHE: false<br>CONCATENATE_SCRIPTS: undefined<br>COMPRESS_SCRIPTS: undefined<br>COMPRESS_CSS: undefined<br>WP_ENVIRONMENT_TYPE: production<br>WP_DEVELOPMENT_MODE: undefined<br>DB_CHARSET: utf8mb4<br>DB_COLLATE: utf8mb4_general_ci<br><br>### wp-filesystem ###<br><br>wordpress: not writable<br>wp-content: not writable<br>uploads: writable<br>plugins: not writable<br>themes: not writable<br>fonts: writable<br>mu-plugins: not writable<br><br>### jetpack ###<br><br>site_id: 147862304<br>ssl_cert: No<br>time_diff: false<br>version_option: 13.7:1724264444<br>old_version: 13.6:1724264444<br>public: Public<br>master_user: #1 redacted<br>is_offline_mode: off<br>is_offline_mode_constant: off<br>current_user: #12345678 redacted<br>tokens_set: Blog <br>blog_token: zs7&99niO&x6RDay61!s55Q#3L8hY9Sc<br>user_token: Not set.<br>version: 13.7<br>jp_plugin_dir: /var/www/wp-content/mu-plugins/jetpack-13.7/<br>plan: complete<br>protect_header: false<br>full_sync: {"started":"Wed, 03 Jul 2024 16:41:47 +0000","finished":"Wed, 03 Jul 2024 16:41:49 +0000","progress":{"options":{"finished":true},"functions":{"finished":true},"constants":{"finished":true},"users":{"total":0,"sent":0,"finished":true,"last_sent":"~0"},"network_options":{"finished":true}},"config":{"options":true,"functions":true,"constants":true,"users":[145565787],"network_options":true}}<br>sync_size: 1<br>sync_lag: 3 seconds<br>full_sync_size: undefined<br>full_sync_lag: 0 seconds<br>idc_urls: {"home":"https:\/\/redacted.com","siteurl":"https:\/\/redacted.com","WP_HOME":"","WP_SITEURL":""}<br>idc_error_option: false<br>idc_optin: false<br>cxn_tests: All Pass.<br><br>### acf ###<br><br>version: 6.3.5<br>plugin_type: PRO<br>activated: false<br>activated_url: undefined<br>license_type: undefined<br>license_status: undefined<br>subscription_expires: undefined<br>ui_field_groups: 1<br>php_field_groups: 0<br>json_field_groups: 49<br>rest_field_groups: 0<br>post_types_enabled: true<br>ui_post_types: 22<br>json_post_types: 0<br>ui_taxonomies: 12<br>json_taxonomies: 0<br>ui_options_pages_enabled: true<br>ui_options_pages: 0<br>json_options_pages: 0<br>php_options_pages: 4<br>rest_api_format: light<br>registered_acf_blocks: 0<br>blocks_per_api_version: <br>blocks_per_acf_block_version: <br>blocks_using_post_meta: 0<br>preload_blocks: true<br>admin_ui_enabled: false<br>field_type-modal_enabled: true<br>field_settings_tabs_enabled: false<br>shortcode_enabled: true<br>registered_acf_forms: 0<br>json_save_paths: 1<br>json_load_paths: 1<br><br>### parsely (18) ###<br><br>apikey: redacted.com<br>content_id_prefix: undefined<br>use_top_level_cats: false<br>custom_taxonomy_section: category<br>cats_as_tags: true<br>content_helper: <br>	ai_features_enabled: 1<br>	smart_linking: Array<br>	title_suggestions: Array<br>	excerpt_suggestions: Array<br>track_authenticated_users: true<br>lowercase_tags: true<br>force_https_canonicals: true<br>track_post_types: <br>	0: post<br>	1: recipes<br>	2: contests<br>	3: diy<br>	4: tips<br>	5: product-reviews<br>	6: deals<br>	7: headers<br>	8: news<br>track_page_types: <br>	0: page<br>full_metadata_in_non_posts: false<br>disable_javascript: false<br>disable_amp: false<br>meta_type: repeated_metas<br>logo: https://redacted.com/wp-content/uploads/2012/1/logo.jpg<br>disable_autotrack: false<br>plugin_version: 3.16.4<br><br>

Some identifying elements have been redacted but I don’t believe they will affect your analysis.

I use this plugin on many different sites and would like to get to the bottom of this issue. The only related info I can find is in this ticket, but unfortunately removing and reinstalling has not helped.

Thanks in advance!