mysql_error on line 145

SELECT mainImages.id AS img_id, mainImages.project_id AS pro_id, countries.country, projects.city, projects.project FROM r_designers LEFT JOIN (SELECT * FROM images ORDER BY main DESC, id ASC) AS mainImages ON r_designers.project_id = mainImages.project_id LEFT JOIN projects ON projects.id = mainImages.project_id LEFT JOIN countries ON countries.id = projects.country_id WHERE r_designers.project_id != 1111 AND r_designers.designer_id = 92 AND mainImages.project_id != '' AND projects.status = 5 GROUP BY mainImages.project_id ORDER BY RAND() LIMIT 3

Error writing file '/tmp/MYBofZyN' (Errcode: 28)