Go to Site Administration -> Plugins -> Caching -> Configuration Add new instance for File Cache - File Cache -> Add instance Confirm that you can see the Asynchronously purge directory setting Fill in all the details Store name: Take note of this. Cache path: A folder writable by the web server. e.g. in your moodledata folder, " /path/to/moodledata/testcache/filestorecaching " Single directory store setting should NOT be checked Tick 'Asynchronously purge directory' Click on Save changes Back on the Cache administration page, search for Config settings (core config) under " Known cache definitions " and click on Edit mappings Change this core/config store mappings Primary cache to the file cache store that you created earlier. Click on Save changes A new cache revision directory should get created in the file store cache instance's Cache path directory The new cache revision will be CACHE REV DIRECTORY = /path/to/moodledata/testcache/filestorecaching/core_config/<YmdHis> where YmdHis = current year month day hour minutes seconds e.g. /path/to/moodledata/testcache/filestorecaching/core_config/20211208095836 Confirm that core/config cache files are created in this CACHE REV DIRECTORY Confirm the word count of this directory e.g. find <CACHE REV DIRECTORY> -type f | xargs wc -w | tail -1 Now let's change some core config settings. Go to Site Administration -> Server -> Maintenance mode Add in some two lines of text in Optional maintenance message (maintenance_message) setting Click on Save changes Confirm the word count of this directory e.g. find <CACHE REV DIRECTORY> -type f | xargs wc -w | tail -1 The current word count should be higher than Step 6 Make a note of this word count Now let's purge caches for core/config . Go to Site Administration -> Plugins -> Caching -> Configuration Search for Config settings (core/config) from the list Click on Purge A new cache revision directory will be created on successful purge in the Cache path directory Cache files will be created in this new CACHE REV DIRECTORY Old CACHE REV DIRECTORY should exist. Confirm the word count of this directory, it should be the same as noted in Step 17 Adhoc task \cachestore_file\task\asyncpurge will be created to delete the Old CACHE REV DIRECTORY (Check  mdl_task_adhoc table) Repeat Steps 16 and 17. Old CACHE REV DIRECTORY should exist. Confirm the word count of this directory, it should be the same as noted in Step 17 Any core config changes made will update relevant cache files in the new CACHE REV DIRECTORY Execute the Adhoc task created in Step 9 via the CLI php admin/cli/adhoc_task.php --execute Confirm the Old CACHE REV DIRECTORY has been deleted.