Today I've made an upgrade to 4.71.2 Yesterday I did it once, but there was an 505 error, so I've decided to delete everything, and create a new clean install. Deleted everything, and upload every file through FTP, set the config.php, and copy back the attachments. I've run the setup, it was fast and success. Then I rebuild the cache as in the documentation says, and deleted the setup directory. Now, when I want to reply to a ticket, I've got this message: Warning mkdir(): Operation not permitted (./__swift/thirdparty/SwiftMailer/classes/SwiftMailer/KeyCache/DiskKeyCache.php:279) I opened this file, and inserted this: var_dump($cacheDir); And here is the funny part. The cache direcotory is: string(37) "/tmp/129f487d17157ae756aa13635a955a7d" It's a debian box, and I've checked the tmp directory, it has permission 777 with t flag: drwxrwxrwt 3 root root 4096 Nov 12 09:17 tmp What could be the problem now? Why keycache file can not create a directory in a proper set tmp directory?