clicking on an unread message always redirects to the same post

[Harrison76]

hello everyone,
on our forum we have had this problem for a long time: in a thread where we have read some posts and others have not, if we click on the days after via unread messages it always makes us go to the same post, even though we have already read it. It seems that the problem can be solved by clearing the browser cache.

A user suggested:

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change the web server header by inserting:
Cache-Control: max-age=0, no-cache

instead of:
Cache-Control: private, no-cache="set-cookie".

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which I don't know if it will be a solution, and I would like to try it but I don't know how to do it. Does anyone know about this problem, what it is and how to solve it? Thanks

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[Brf]

This problem is often caused by deleting a user from the database and leaving their posts intact. The posts no-longer show in viewtopic, but still are counted when traversing the topic.

[Harrison76]

I don't think it's that: it happens very often and we hardly ever delete users.
And then it doesn't correspond to the fact that if you clear the browser cache the problem disappears