Anyone can open the forum thread dedicated to a topic with the so called t-page like this:
example.com/forum/posts/t123-a-subject
However, the board index allows the user to open the last post in any topic using the so called m-page. Below is an example for the same thread:
example.com/forum/posts/m456-a-subject#post456
I blocked all pages starting with /forum/posts/m in robots.txt to avoid the duplicate pages error while the Google bot is crawling our forum. But the new Google Search Console shows a lot of the following warnings related to this pages: "Indexed, though blocked by robots.txt".
To solve the problem, we need to add the 'noindex' meta-tag to all m-pages. Is there a way to do this in the current forum engine we are using (2.2.4.14)? If not, add this as a suggestion to your to-do list for the future updates.