« MODx Parse Error »

MODx encountered the following error while attempting to parse the requested resource:
« Execution of a query to the database failed - Can't create/write to file '/tmp/#sql_36f5_0.MYI' (Errcode: 12) »
      SQL: SELECT t1.contentid, t1.value, t2.pagetitle FROM `modx_site_tmplvar_contentvalues` AS t1 LEFT JOIN `modx_site_content` AS t2 ON t1.contentid=t2.id WHERE t1.tmplvarid=2 AND t2.published=1 AND t2.parent=15 AND t2.deleted=0 ORDER BY t1.value DESC LIMIT 0,10
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Parser timing
  MySQL: 0.0089 s(28 Requests)
  PHP: 0.8444 s 
  Total: 0.8533 s