TYPO3 Core

Out of curiosity: Why did you configure APCu for TYPO3 and did not enable it for CLI?
A fallback makes little to no sense, if you want to warm up caches via CLI that are then not used in the frontend.

I seem to miss something here, please try to describe your usecase in a bit more detail.

You're right. It's probably not an issue of TYPO3.
Checking with Hoster for PHP settings...
Can probably be closed.
Thanks for the quick response.

Side-note: Fresh TYPO3 installations will use APCu if it's available for the web-context (see ApcuPreset), and PHP 7.1 (at least on Ubuntu 17.10) does not enable the according flag in PHP-CLI per default.

Work-around (example for Ubuntu 17.10):
Modify /etc/php/7.1/cli/conf.d/20-apcu.ini
Add apc.enable_cli=on

IMHO this issue is not solved and it is a TYPO3 issue:

• if APCu is available it is recommend as Extbase-Object-Cache in the Installtool in the Configuration Presets
• the constructor of `TYPO3\CMS\Core\Cache\Backend\ApcuBackend` throws an Execption if `PHP_SAPI === 'cli' && ini_get('apc.enable_cli') == 0` allthough
• the documentation for `apc.enable_cli` [1] says
  

  Mostly for testing and debugging. Setting this enables APC for the CLI version of PHP. 
  Under normal circumstances, it is not ideal to create, populate and destroy the APC cache on every CLI request,
  but for various test scenarios it is useful to be able to enable APC for the CLI version of PHP easily. 
  

• if enabled for the CLI, APCu will most probably have no positive effect since the cache is created, populated AND destroyed for each call (and not re-used later on)

• silently ignore the APCu-cache in CLI (use NullBackend instead)
• optionally log a message

see https://forge.typo3.org/issues/78140

[1] http://php.net/manual/en/apc.configuration.php#ini.apc.enable-cli

I agree with Dirk Wenzel. Most hosters do not allow APCu on CLI.

My workaround is to change the following to AdditionalConfiguration.php

if (php_sapi_name() == 'cli') {
    /** @var ConfigurationManager $configurationManager */
    $configurationManager = GeneralUtility::makeInstance(ConfigurationManager::class);
    $GLOBALS['TYPO3_CONF_VARS']['SYS']['caching'] = $configurationManager->getDefaultConfiguration()['SYS']['caching'];
}