I often need to upgrade DNN and I often lose this link, so I decided to put it somewhere I would remember.
To upgrade DNN: DNN Platform Upgrades — DNN Docs (dnncommunity.org)
And if that link ever goes away this is the summary of the steps to upgrade DNN.
Step 1 Prepare
Know your current and desired DNN version, download the appropriate upgrade ZIP packages, check the system requirements and third-party extensions compatibility, and test the upgrade on a non-production environment if possible.
For a suggested upgrade path visit this DNN Platform Suggested Upgrade Path — DNN Docs (dnncommunity.org)
In the web.config, confirm AutoUpgrade is set to false.
Step 2 Take Website Offline
Add an app_offline.htm file to the root of the site to prevent any access or changes to the site by other users.
Step 3 Make a Backup
Backup files and database: Manually copy all files, folders and subfolders to a protected location, and use Microsoft SQL Server Management Studio (SSMS) or other tools to make a database backup.
Step 4 Apply Upgrade Package
Extract the desired upgrade ZIP package to the root of the website or copy the extracted files from a temporary location.
Step 5 Bring website Online
Remove the app_offline.htm file from the root of the site to allow access to the site pages.
Step 6 Initiate upgrade
Go to the install URL (e.g., http://{Domain}/install/install.aspx?mode=upgrade) to start the upgrade process and follow the instructions on the screen.
Step 7 Check for errors
Review the upgrade log file and the event viewer for any errors or warnings that may have occurred during the upgrade.
Step 8 Test
Verify that the site is working as expected, and that all features and functionalities are intact.