Update guides say "Upload the contents of the 3.1.x Full Package into your forum's directory."

On some OS's .htaccess is invisible, and users have already been upgrading and not copying this file over, resulting in the very least, broken URL rewriting functionality.

Update guides need to append to the above line something like, "Make sure to also copy the .htaccess file in the root of phpBB, it may be invisible."

Locations:
https://www.phpbb.com/support/documents.php?mode=install&version=3&sid=0c0521ee3f4f3e27d1805ebcf564a8ac#update30

https://www.phpbb.com/community/docs/INSTALL.html#update30

https://www.phpbb.com/support/docs/en/3.1/ug/upgradeguide/upgrade3/

https://download.phpbb.com/pub/documentation/3.1/ascraeus_documentation.pdf