Thread:Extension talk:ParserFunctions/on install: Unable to move the new CDB file into place/reply (2)

As it turns out: as root you can create the cache directory everywhere you want, but it can't be read by apache. I found cdb files in /tmp /var/www/html/cache /var/www/html/wiki/cache

all because of typos and wrong entries in LocalSettings.php and because I did not start >php maintenance/rebuildLocalisation.php after each edit

All is well now