I just removed all old files from 2016, the new files from the update pack were all ready present. This fixed the problem. Thanks for the quick fix provided.
I'll walk throug all files and remove the old ones to keep this install as clean as possible.
One more problem. The forum_threads_list_panel.php on the home page has an "old" style link: https://router-info.com/infusions/forum/viewthread.php?thread_id=1&pid=1#post_1
When clicking it a rewrites perfectly to: https://router-info.com/forum/thread/view-1/1/Asus-AC-87U-Merlin-Firmware#post_1
I would like the links in forum_threads_list_panel.php also to be SEF to avoid double urls and get a seo penalty.
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