For about a day now, trying to download a DLC will fail with the error,

Code:
    (setDLCKey2Cache) Can not write in file ./inc/pages/dlcapi/cache/dlcapicache.txt
    (createDLC) Could not save cache file for keys
I personally experienced this earlier this week for a few hours after which the problem seemed to have been solved.

This time, it's been almost a full day, and it's still broken.