Discuz! info: MySQL Query Error

Time: 2016-9-30 4:34pm
Script: /index.php

SQL: SELECT t.*, f.name FROM cdb_threads t, cdb_forums f WHERE t.fid<>'0' AND f.fid=t.fid ORDER BY t.dateline DESC LIMIT 0, 10
Error: Error writing file '/tmp/MYvq1Dm6' (Errcode: 28)
Errno.: 3

Similar error report has beed dispatched to administrator before.