This 500 error did start with last plugin update.
It’s instantly fixed when using a backup of the .htaccess file.
Old .htaccess :
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
.htaccess after last update :
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /fr/
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /fr/index.php [L]
</IfModule>
So pretty much the same, though one has a language set for some reason.
Not sure if this is the same issue for your website, but it did fix the 500 error issue on my managed website using this plugin.
@sdenis Is the “/fr/” required in .htaccess or not?