We recommend that you review Post-installation Messages immediately after updating the Joomla! CMS.
If there are any NEW messages after you update your website's Joomla! CMS then you will see a NOTICE at the top of the screen when you sign into your website's Control Panel.
Messages should not be ignored if they impact on SECURITY or SEO.
But the choice is yours!
To hide any one message simply select the HIDE THIS MESSAGE button.
Reviewing Hidden Messages
If later you want to review previous messages you can.
Example Messages which impact on SECURITY
Did you update a website using an older version of Joomla! CMS but ignored these messages?
If YES then re-read and act on the messages shown below.
Need help, just ask.
Post Joomla! 3.9.21 Security Update
Post Joomla! 3.9.19 Security Update
Post Joomla! 3.9.3 Security Update
Post Joomla! 3.8.8 Security Update