TYPO3 Core

If creation of ClassLoader caching isn't possible, course an exception is thrown in this process, we get a stale lock file.
Also we can get a unclean cache, as in the example the ClassAliases cache isn't saved but we don't check this again.

Example shortened backtrace what may happening:

Fatal error:  Uncaught exception 'BadFunctionCallException' with  message 'TYPO3 Fatal Error: Extension key "external_import" is NOT  loaded!' in 
/typo3/sysext/core/Classes/Utility/ExtensionManagementUtility.php:122 
Stack  trace:
#0  /typo3conf/ext/ppi_..._showtime/ext_autoload.php(4):   TYPO3/CMS/Core/Utility/ExtensionManagementUtility::extPath('external_import',  'interfaces/inte...')
#1  /typo3/sysext/core/Classes/Package/Package.php(292):  require('/...')
#2  /typo3/sysext/core/Classes/Core/ClassLoader.php(570):  TYPO3/CMS/Core/Package/Package->getClassFilesFromAutoloadRegistry()
#3  /typo3/sysext/core/Classes/Core/ClassLoader.php(496):   TYPO3/CMS/Core/Core/ClassLoader->loadClassFilesFromAutoloadRegistryIntoRuntimeClassInformationCache(Array)
#4   /typo3/sysext/core/Classes/Core/ClassLoader.php(452):  TYPO3/CMS/Core/Core/ClassLoader->buildPackageNamespacesAndCl in /typo3/sysext/core/Classes/Utility/ExtensionManagementUtility.php on line 122

This example happened after git updating an extension which now depends on another extension which isn't installed. Afterwards the ClassLoader cache was cleared.