Looking at the forums on the ExpressionEngine site, it appears that the Forum Add-on used is either a customised version, or it has undocumented features.
For example: - The links to each forum topic is structured as “/<site_url>/forums/viewthread/<thread-ID>/” with the Forum Add-on. But the links in ExpressionEngine forums are structured as “/<site_url>/forums/topics/<topic-ID>/<topic-title>”.
When trying such URLs with ExpressionEngine (6.x latest) and latest compatible Forum version, it gives this error - “The page you requested was not found”. The HTTP Response Code is 200 though.
Can anyone share tips on how this customisation of URLs is being done? Are there special path variables that we can use in the forum templates to get the link with topic ID and topic title included in the URL?
I haven’t done enough work with the Forums add-on to be knowledgeable in what can be customized or not. However, I can tell you that the Forums on this site use a custom add-on the ExpressionEngine team created (several years ago). At the time it was going to be the next iteration of the Forums module. Unfortunately, it’s never received the love it needs to be released to the public. Maybe one day we’ll be able to come back to it.