MyBB SQL Error

MyBB has experienced an internal SQL error and cannot continue.

SQL Error:
1062 - Duplicate entry '0' for key 2
Query:
REPLACE INTO bb_sessions SET `uid`='0',`sid`='97f41019222d507df797eb4dcb0a1277',`time`='1414772805',`ip`='54.197.111.87',`location`='/forums/index.php?',`useragent`='CCBot/2.0 (http://commoncrawl.org/faq/)',`location1`='0',`location2`='0',`nopermission`='0'