Magento folders that must be writeable - chmod magento folders. The folders/files that must be writeable (chmod 777 with subfolders) in magento are: /yourrootfolder/var/ used by magento for the cache, reports, logs /yourrootfolder/media/ used by magento for the images /yourrootfolder/app/etc/ ONLY for OLDER magento version prior to 1.4 to update use_cache.ser only (afaik).