Nextcloud version = 22.2.0.2
Operating system and version = CentOS 7.9
Apache version = 2.4.6
PHP version = 7.3.32
The issue you are facing:
Cannot get APcu to function for background jobs following upgrade.
Is this the first time you’ve seen this error? = Yes
Steps to replicate it:
1. Upgrade PHP from 7.2 to 7.3 (remi), upgrade NextCloud incrementally from 18 to 22
2. Enter in terminal: “php -f www/html/public_html/cron.php”
3. Results in error: “OC\HintException: [0]: Memcache \OC\Memcache\APCu not available for local cache (Is the matching PHP module installed and enabled?)”
**The output of your Nextcloud log in Admin > Logging
“No server logs - Everything is working fine”
**The output of your config.php:
<?php
$CONFIG = array (
'instanceid' => 'REMOVED-4-SECURITY',
'passwordsalt' => 'REMOVED-4-SECURITY',
'secret' => 'REMOVED-4-SECURITY',
'trusted_domains' =>
array (
0 => 'REMOVED-4-SECURITY',
1 => 'REMOVED-4-SECURITY',
2 => 'REMOVED-4-SECURITY',
),
'datadirectory' => 'REMOVED-4-SECURITY',
'overwrite.cli.url' => 'REMOVED-4-SECURITY',
'dbtype' => 'mysql',
'version' => '22.2.0.2',
'dbname' => 'REMOVED-4-SECURITY',
'dbhost' => 'localhost',
'dbport' => '',
'dbtableprefix' => 'REMOVED-4-SECURITY_',
'dbuser' => 'REMOVED-4-SECURITY',
'dbpassword' => 'REMOVED-4-SECURITY',
'default_phone_region' => 'US',
'installed' => true,
'log_type' => 'owncloud',
'logfile' => '/var/log/nextcloud.log',
'loglevel' => 0,
'logdateformat' => 'F d, Y H:i:s',
'trashbin_retention_obligation' => 'auto, 3',
'mail_from_address' => 'REMOVED-4-SECURITY',
'mail_smtpmode' => 'smtp',
'mail_domain' => 'REMOVED-4-SECURITY',
// APCu disabled due to error 10/28/2021 due to CRON error - AB
// 'memcache.local' => '\OC\Memcache\APCu',
'memcache.local' => '\\OC\\Memcache\\Redis',
'memcache.locking' => '\\OC\\Memcache\\Redis',
'mysql.utf8mb4' => true,
'redis' =>
array (
'host' => 'localhost',
'port' => 'REMOVED-4-SECURITY',
),
'maintenance' => false,
'theme' => '',
'mail_smtpsecure' => 'tls',
'mail_sendmailmode' => 'smtp',
'mail_smtpauthtype' => 'LOGIN',
'mail_smtpauth' => 1,
'mail_smtphost' => 'REMOVED-4-SECURITY',
'mail_smtpport' => 'REMOVED-4-SECURITY',
'mail_smtpname' => 'REMOVED-4-SECURITY',
'mail_smtppassword' => 'REMOVED-4-SECURITY',
'simpleSignUpLink.shown' => false,
'versions_retention_obligation' => 'auto, 7',
'updater.release.channel' => 'stable',
);
Have searched for the better part of two (2) days attempting to search for a solution on numerous forums to no avail to restore APCu as memory cache following an upgrade of NextCloud from version 18 incrementally to version 22 & upgrading PHP 7.1 to PHP 7.3 (remi)
Background jobs fail, and running from terminal: php -f www/html/public_html/cron.php results in error: OC\HintException: [0]: Memcache \OC\Memcache\APCu not available for local cache (Is the matching PHP module installed and enabled?)
Double checked for required APCu module = ok
Not sure if this is connected or cause, but loading PHP-info results in (none) as the loaded configuration. 
. . .
In addition, no matter the PHP.ini file edited apc.enable_cli remains ‘no’
In the interim, I have as seen in the NextCloud config file above, fallen back to Redis for both local and locking cache.