[Owncloud] Encryption not working in OC 5.0.10

[galahad at ftp83plus.net]

Hello mailing list, 

I have an OC installation running on a shared server. This is version 5.0.10, and PHP is 5.3.8.

I noticed that, despite me activating encryption, my files are still stored as plaintext, as seen in the FTP. In owncloud.log, in /data/, I can see the following, relating to encryption, but I can't understand its source:

{"app":"Encryption library","message":"User account \"Arthur\" is not ready for encryption; configuration started","level":0,"time":1371666032}
{"app":"Encryption library","message":"Decryption (asymmetric) of sealed content failed","level":3,"time":1371666094}
{"app":"hook","message":"error while running hook (OCA\\Encryption\\Hooks::postRename): Cannot mutliKeyEncrypt empty plain content","level":3,"time":1371666094}
{"app":"Encryption library","message":"Encryption of existing files belonging to \"Arthur\" completed","level":1,"time":1371666100}
{"app":"PHP","message":"Cannot mutliKeyEncrypt empty plain content at \/home\/xxxxxx\/public_html\/owncloud\/apps\/files_encryption\/lib\/crypt.php#394","level":4,"time":1371667904}
{"app":"files_encryption","message":"failed to open file \"\/Arthur\/files\/imports\/vCards.vcf.etmp\"","level":3,"time":1371674580}
{"app":"PHP","message":"fopen(crypt:\/\/imports\/vCards.vcf.etmp): failed to open stream: \"OCA\\Encryption\\Stream::stream_open\" call failed at \/home\/xxxxxx\/public_html\/owncloud\/apps\/files_encryption\/lib\/proxy.php#119","level":2,"time":1371674580}
{"app":"PHP","message":"Undefined property: OCA\\Encryption\\Util::$userFilesDir at \/home\/xxxxxx\/public_html\/owncloud\/apps\/files_encryption\/lib\/util.php#1366","level":2,"time":1371742861}
{"app":"PHP","message":"Undefined property: OCA\\Encryption\\Util::$userFilesDir at \/home\/xxxxxx\/public_html\/owncloud\/apps\/files_encryption\/lib\/util.php#1366","level":2,"time":1371742861}

What does it means?

Pat