Magento: ?___SID=U appearing in some urls

Question

Can someone please explain why ?___SID=U is appearing in some Magento URLs on my site and not others?

I think it has something to do with sessions but I am not entir

Answer 1

This is a general Magento 2 bug which is already reported to magento.

Temporary fix is

Go to Document Root, Find .htaccess and add

RewriteCond %{HTTP_HOST} ^abc.com
RewriteRule ^(.*) www.abc.com/$1 [L,R=301]

below.

This should solve the issue. For me this work in M2.1

All the best.

Reference : https://github.com/magento/magento2/issues/5517