Finally,Found the solution!!
error in custom error page,got the solution from https://stackoverflow.com/questions/12760351/getting-404-not-found-error-while-trying-to-use-errordocument.
changed the value of True to False in functions.php
if(($category_name!=”abc”) && ($posttitle!=”)){
global $wp_query;
$wp_query->is_404 = false
;
}
Facing the Same Problem.Also Need a help if anyone can get the Solution for this problem.
any help is greatly appreciated.
Thank you.