When anyone tries to comment on a post, the window goes blank and the comment does not appear to have been recognised by WordPress.
1) The Theme that you are using is missing a critical part of the comment form so WordPress does not know which post the comment refers to. You need to check the comment.php in your Theme and ensure that the following code appears within the form.
<input type=”hidden” name=”comment_post_ID” value=”<?php echo $id; ?>” />
If it is not added then add it in the form of comment.php.
2) If option 1 does not work then have a check with disabling the plugins and enable plugin one by one to find out the culprit.
3) Upgrade your wordpress to the latest version.
4) Check with default theme to rules out theme level problems.