Textpattern CMS support forum
Re: Error 404 Not found after update
etc wrote #316596:
Unless you have heavily customized your setup, you should be able to safely update (merge) the entire
textpatternfolder. Actually, 99% of new code go there, so keeping an old version is hazardous.
+1 on what Oleg recommended.
What you will have to look out for the the
config.php file which should remain as is.