Uncaught exception!

Calling Class: BBR\bbr_forum_threads_class.php
Exception class: bbr_forum_threads_class.php

#0 /home/bestbikingroads/php_includes/BBR/bbr_forum_threads_class.php(20): PDOStatement->execute()
#1 /home/bestbikingroads/public_html/forum/home.php(41): BBR\bbr_forum_threads->get_sticky_posts()
#2 /home/bestbikingroads/public_html/forum/index.php(12): include('/home/bestbikin...')
#3 {main}

SQLSTATE[HY000]: General error: 1021 Disk full (/tmp/#sql_3f4_2.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")