XF 2.0 Deadlock found when trying to get lock

[Codeless]

i am getting this error log in my acp unable to understand

XF Version : 2.0.9
Siropu Ads Manager 2.1.2

Server error log

• XF\Db\DeadlockException: MySQL query error [1213]: Deadlock found when trying to get lock; try restarting transaction
• src/XF/Db/AbstractStatement.php:212
• Generated by: username
• Aug 18, 2018 at 2:32 PM

====

Stack trace
DELETE  FROM `xf_user_remember` WHERE user_id = ? AND expiry_date <= ?
------------

#0 src/XF/Db/Mysqli/Statement.php(196): XF\Db\AbstractStatement->getException('MySQL query err...', 1213, '40001')
#1 src/XF/Db/Mysqli/Statement.php(78): XF\Db\Mysqli\Statement->getException('MySQL query err...', 1213, '40001')
#2 src/XF/Db/AbstractAdapter.php(79): XF\Db\Mysqli\Statement->execute()
#3 src/XF/Db/AbstractAdapter.php(218): XF\Db\AbstractAdapter->query('DELETE  FROM `x...', Array)
#4 src/XF/Repository/UserRemember.php(106): XF\Db\AbstractAdapter->delete('xf_user_remembe...', 'user_id = ? AND...', Array)
#5 src/XF/Entity/UserRemember.php(89): XF\Repository\UserRemember->applyUserRememberRecordLimit(55429)
#6 src/XF/Mvc/Entity/Entity.php(1145): XF\Entity\UserRemember->_postSave()
#7 src/XF/Repository/UserRemember.php(15): XF\Mvc\Entity\Entity->save()
#8 src/XF/ControllerPlugin/Login.php(216): XF\Repository\UserRemember->createRememberRecord(55429)
#9 src/XF/ControllerPlugin/Login.php(182): XF\ControllerPlugin\Login->createVisitorRememberKey()
#10 src/XF/Pub/Controller/Login.php(106): XF\ControllerPlugin\Login->completeLogin(Object(Siropu\AdsManager\XF\Entity\User), true)
#11 src/XF/Mvc/Dispatcher.php(249): XF\Pub\Controller\Login->actionLogin(Object(XF\Mvc\ParameterBag))
#12 src/XF/Mvc/Dispatcher.php(89): XF\Mvc\Dispatcher->dispatchClass('XF:Login', 'login', 'html', Object(XF\Mvc\ParameterBag), '', Object(XF\Pub\Controller\Login), NULL)
#13 src/XF/Mvc/Dispatcher.php(41): XF\Mvc\Dispatcher->dispatchLoop(Object(XF\Mvc\RouteMatch))
#14 src/XF/App.php(1931): XF\Mvc\Dispatcher->run()
#15 src/XF.php(328): XF\App->run()
#16 index.php(13): XF::runApp('XF\\Pub\\App')
#17 {main}

[SIZE=5][B]Request state[/B][/SIZE] array(4) { ["url"] => string(12) "/login/login" ["referrer"] => string(31) "https://sitename.com/login" ["_GET"] => array(0) { } ["_POST"] => array(4) { ["login"] => string(10) "username" ["password"] => string(8) "********" ["remember"] => string(1) "1" ["_xfToken"] => string(8) "********" } }