No, the error with the duplicate content appeared again.
http://www.screamingfrog.co.uk/seo-spider/ this is a spider tool you can use for free.
Scan my homepage, go to “Internal” tab an click filter->HTML (see only pages and categories) and you will see what I mean:
you can reach every page (not only the categories) normal and with ?s= at the end. If you right click on a url you can open it in the browser.
Do this with the normal url and with the url/?s= at the end
You see its the same page reachable under 2 urls. Thats duplicate content.
If you open a category with ?s= at the end you see search results in this category – thats okay so far.
You can go to my admin area and remove the widget (design -> widgets -> page sidebar) and after this on top of admin area there is WP Rocket -> delete cache and after this, please spider my page again with screaming frog:
you see only half of the number of urls than before – the ?=s urls for the normal pages are gone!
Many thanks for your help…