Thanks for the heads up.
As mentioned, I just code for fun.
Here is an alternative to modifying the core code of the plugin.
Do steps 1 and 2 from the original post.
Instead of step 3, use this code in the your theme’s files where get_avatar is used.
<?php $user_info = get_userdata($post->post_author);
$loginname = $user_info->user_login ;
$DefaultAvatar = '/wp-content/uploads/defaultavatars/'.$loginname.'.png';
$DefaultAvatarLink = get_bloginfo('url').$DefaultAvatar ;
if (!file_exists($_SERVER['DOCUMENT_ROOT'].$DefaultAvatar)) {$DefaultAvatarLink = "" ;}
echo get_avatar($post->post_author, '40' , $DefaultAvatarLink); ?>
Change the 40 in the last line above to whatever you want the avatar size to be.
The line to be replaced with code above will probably look like <?php echo get_avatar($post->post_author, '40'); ?>
The problem is that this will not work in the comments section or with other plugins like https://www.ads-software.com/extend/plugins/author-avatars/
