An invalid log directory is a "silent error": you can set it to something wrong and nothing would change, your site will continue to work as usual.
However, when Joomla (or any other component, for example Admin Tools) will try to log some information (for example an invalid login or a security exception) it won't find a valid folder and won't log anything.
For example Admin Tools logs all security exceptions in two places: inside the database and in a text file inside the log folder.
Database records are displayed in the Security exceptions page, while in the log file you will find detailed information about all blocked requests, along with the actual data posted to your Joomla site. This text file is very useful to analyze threats and attack types performed vs your site.
Sadly if Joomla log folder is not correct, you will miss these important info, that's why we warn you to fix the log path before continuing.
Davide Tampellini
Developer and Support Staff
🇮🇹Italian: native 🇬🇧English: good • 🕐 My time zone is Europe / Rome (UTC +1)
Please keep in mind my timezone and cultural differences when reading my replies. Thank you!