MySQL error in file: /engine/init.php at line 304

Error Number: 1

The Error returned was:
Can't create/write to file '/tmp/#sql_435_0.MYI' (Errcode: 28)

SQL query:

SELECT category, COUNT(*) AS count FROM dle_post WHERE approve=1 AND date < '2020-08-06 07:46:21' GROUP BY category