joomla bugs error

[2dmaster]

when logout from administrator get error !j3.5.1

Warning: mysqli_errno() expects parameter 1 to be mysqli, boolean given in /home/domains/....ru/public_html/libraries/joomla/database/driver/mysqli.php on line 987
Warning: mysqli_error() expects parameter 1 to be mysqli, boolean given in /home/domains/....ru/public_html/libraries/joomla/database/driver/mysqli.php on line 1001
Error displaying the error page: Could not connect to MySQL.: Could not connect to MySQL.
but i set no display errors

next CF filter (customfieldsforall)
Strict Standards: Declaration of CustomfieldsForAllFilter::getInstance() should be compatible with & JFilterInput::getInstance($tagsArray = Array, $attrArray = Array, $tagsMethod = 0, $attrMethod = 0, $xssAuto = 1, $stripUSC = -1) in /home/domains/....ru/public_html/plugins/vmcustom/customfieldsforall/helpers/filter.php on line 249

[Studio 42]

Hi,
Check with the customfieldsforall developer, i think he forced the error display.