1. Reference: Migrating (replacing) CentOS 7 with Alibaba Cloud Linux 3 in Alibaba Cloud ECS. After redeploying the WordPress system disk, it prompted: There has been a critical error on this website. See Figure 1.
2. Learn more about troubleshooting WordPress. Enable developer-specific: WordPress debug mode. Edit wp-config.php.
PHP
/**
* 开发者专用：WordPress 调试模式。
*
* 将这个值改为“true”，WordPress 将显示所有用于开发的提示。
* 强烈建议插件开发者在开发环境中启用本功能。
*/
define('WP_DEBUG', true);
3. Refresh the page again, and errors are reported.
Plaintext
Deprecated: Return type of HM\BackUpWordPress\CleanUpIterator::accept() should either be compatible with FilterIterator::accept(): bool, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /data/wwwroot/www.shuijingwanwq.com/wp-content/plugins/backupwordpress/classes/class-path.php on line 456
Fatal error: Uncaught Error: Undefined constant "wp_cumulus_widget" in /data/wwwroot/www.shuijingwanwq.com/wp-content/plugins/wp-cumulus/wp-cumulus.php:375 Stack trace: #0 /data/wwwroot/www.shuijingwanwq.com/wp-includes/class-wp-hook.php(308): widget_init_wp_cumulus_widget() #1 /data/wwwroot/www.shuijingwanwq.com/wp-includes/class-wp-hook.php(332): WP_Hook->apply_filters() #2 /data/wwwroot/www.shuijingwanwq.com/wp-includes/plugin.php(517): WP_Hook->do_action() #3 /data/wwwroot/www.shuijingwanwq.com/wp-includes/widgets.php(1854): do_action() #4 /data/wwwroot/www.shuijingwanwq.com/wp-includes/class-wp-hook.php(308): wp_widgets_init() #5 /data/wwwroot/www.shuijingwanwq.com/wp-includes/class-wp-hook.php(332): WP_Hook->apply_filters() #6 /data/wwwroot/www.shuijingwanwq.com/wp-includes/plugin.php(517): WP_Hook->do_action() #7 /data/wwwroot/www.shuijingwanwq.com/wp-settings.php(623): do_action() #8 /data/wwwroot/www.shuijingwanwq.com/wp-config.php(87): require_once('...') #9 /data/wwwroot/www.shuijingwanwq.com/wp-load.php(50): require_once('...') #10 /data/wwwroot/www.shuijingwanwq.com/wp-blog-header.php(13): require_once('...') #11 /data/wwwroot/www.shuijingwanwq.com/index.php(17): require('...') #12 {main} thrown in /data/wwwroot/www.shuijingwanwq.com/wp-content/plugins/wp-cumulus/wp-cumulus.php on line 375
4. I found that all the errors were from plugins, so I decided to find a way to disable the plugins causing the errors first. Since I could not access the WordPress dashboard, I needed to disable the plugins in a different way. Reference: How to Disable WordPress Plugins (4 Methods).
5. Reference: How to Disable WordPress Plugins via phpMyAdmin. Its essence is manipulating data in the database.
6. Back up the database before manipulating the data. Open the wp_options table. See Figure 2.
7. In the options table, look for the active_plugins entry in the option_name column. Execute the following SQL query. See Figure 3.
SQL
SELECT * FROM `wp_options` WHERE `option_name` = 'active_plugins'
8. Copy the value of the option_value column from the query result record, and use an online PHP deserialization tool.
Plaintext
a:14:{i:0;s:53:"accelerated-mobile-pages/accelerated-moblie-pages.php";i:1;s:19:"akismet/akismet.php";i:2;s:35:"backupwordpress/backupwordpress.php";i:3;s:33:"classic-editor/classic-editor.php";i:4;s:36:"contact-form-7/wp-contact-form-7.php";i:5;s:45:"disable-google-fonts/disable-google-fonts.php";i:6;s:72:"golang-brush-for-syntaxhighlighter-evolved/syntaxhighlighter-GoBrush.php";i:7;s:25:"hueman-addons/ha-fire.php";i:8;s:15:"light/light.php";i:9;s:33:"nimble-builder/nimble-builder.php";i:10;s:47:"regenerate-thumbnails/regenerate-thumbnails.php";i:11;s:39:"syntaxhighlighter/syntaxhighlighter.php";i:12;s:25:"wp-cumulus/wp-cumulus.php";i:13;s:27:"wp-pagenavi/wp-pagenavi.php";}
Array
(
[0] => accelerated-mobile-pages/accelerated-moblie-pages.php
[1] => akismet/akismet.php
[2] => backupwordpress/backupwordpress.php
[3] => classic-editor/classic-editor.php
[4] => contact-form-7/wp-contact-form-7.php
[5] => disable-google-fonts/disable-google-fonts.php
[6] => golang-brush-for-syntaxhighlighter-evolved/syntaxhighlighter-GoBrush.php
[7] => hueman-addons/ha-fire.php
[8] => light/light.php
[9] => nimble-builder/nimble-builder.php
[10] => regenerate-thumbnails/regenerate-thumbnails.php
[11] => syntaxhighlighter/syntaxhighlighter.php
[12] => wp-cumulus/wp-cumulus.php
[13] => wp-pagenavi/wp-pagenavi.php
)
9. Remove the plugins backupwordpress/backupwordpress.php and wp-cumulus/wp-cumulus.php from the deserialized result, then store the PHP serialized result back into the value of the option_value column. The PHP code implementation is as follows.
PHP
<?php
$a = 'a:14:{i:0;s:53:"accelerated-mobile-pages/accelerated-moblie-pages.php";i:1;s:19:"akismet/akismet.php";i:2;s:35:"backupwordpress/backupwordpress.php";i:3;s:33:"classic-editor/classic-editor.php";i:4;s:36:"contact-form-7/wp-contact-form-7.php";i:5;s:45:"disable-google-fonts/disable-google-fonts.php";i:6;s:72:"golang-brush-for-syntaxhighlighter-evolved/syntaxhighlighter-GoBrush.php";i:7;s:25:"hueman-addons/ha-fire.php";i:8;s:15:"light/light.php";i:9;s:33:"nimble-builder/nimble-builder.php";i:10;s:47:"regenerate-thumbnails/regenerate-thumbnails.php";i:11;s:39:"syntaxhighlighter/syntaxhighlighter.php";i:12;s:25:"wp-cumulus/wp-cumulus.php";i:13;s:27:"wp-pagenavi/wp-pagenavi.php";}';
$b = unserialize($a);
print_r($b);
$c = [
'accelerated-mobile-pages/accelerated-moblie-pages.php',
'akismet/akismet.php',
'classic-editor/classic-editor.php',
'contact-form-7/wp-contact-form-7.php',
'disable-google-fonts/disable-google-fonts.php',
'golang-brush-for-syntaxhighlighter-evolved/syntaxhighlighter-GoBrush.php',
'hueman-addons/ha-fire.php',
'light/light.php',
'nimble-builder/nimble-builder.php',
'regenerate-thumbnails/regenerate-thumbnails.php',
'syntaxhighlighter/syntaxhighlighter.php',
'wp-pagenavi/wp-pagenavi.php'
];
print_r($c);
$d = serialize($c);
print_r($d);
exit;
?>Plaintext
Array
(
[0] => accelerated-mobile-pages/accelerated-moblie-pages.php
[1] => akismet/akismet.php
[2] => classic-editor/classic-editor.php
[3] => contact-form-7/wp-contact-form-7.php
[4] => disable-google-fonts/disable-google-fonts.php
[5] => golang-brush-for-syntaxhighlighter-evolved/syntaxhighlighter-GoBrush.php
[6] => hueman-addons/ha-fire.php
[7] => light/light.php
[8] => nimble-builder/nimble-builder.php
[9] => regenerate-thumbnails/regenerate-thumbnails.php
[10] => syntaxhighlighter/syntaxhighlighter.php
[11] => wp-pagenavi/wp-pagenavi.php
)
a:12:{i:0;s:53:"accelerated-mobile-pages/accelerated-moblie-pages.php";i:1;s:19:"akismet/akismet.php";i:2;s:33:"classic-editor/classic-editor.php";i:3;s:36:"contact-form-7/wp-contact-form-7.php";i:4;s:45:"disable-google-fonts/disable-google-fonts.php";i:5;s:72:"golang-brush-for-syntaxhighlighter-evolved/syntaxhighlighter-GoBrush.php";i:6;s:25:"hueman-addons/ha-fire.php";i:7;s:15:"light/light.php";i:8;s:33:"nimble-builder/nimble-builder.php";i:9;s:47:"regenerate-thumbnails/regenerate-thumbnails.php";i:10;s:39:"syntaxhighlighter/syntaxhighlighter.php";i:11;s:27:"wp-pagenavi/wp-pagenavi.php";}
SQL
UPDATE `shuijingwanwq`.`wp_options` SET `option_value`='a:12:{i:0;s:53:"accelerated-mobile-pages/accelerated-moblie-pages.php";i:1;s:19:"akismet/akismet.php";i:2;s:33:"classic-editor/classic-editor.php";i:3;s:36:"contact-form-7/wp-contact-form-7.php";i:4;s:45:"disable-google-fonts/disable-google-fonts.php";i:5;s:72:"golang-brush-for-syntaxhighlighter-evolved/syntaxhighlighter-GoBrush.php";i:6;s:25:"hueman-addons/ha-fire.php";i:7;s:15:"light/light.php";i:8;s:33:"nimble-builder/nimble-builder.php";i:9;s:47:"regenerate-thumbnails/regenerate-thumbnails.php";i:10;s:39:"syntaxhighlighter/syntaxhighlighter.php";i:11;s:27:"wp-pagenavi/wp-pagenavi.php";}' WHERE `option_id`=35;
10. After reverting the changes made in step 2, refresh the page again, and the site displays normally.