How to upgrade DNN.
Upgrading DotNetNuke can either be a breeze, or a total pain, depending on certain circumstances.
First you need to ask yourself some questions:
What version do I have?
If my website was created by a previous developer, did they make changes to DNN Core?
What DNN version am I upgrading to?
Check for Custom Code
After you've used the admin to determine what version of DotNetNuke you've got, now you'll need to make sure the previous developer didn't make any changes. To check, download another copy of DotNetNuke that matches the version you have. Compare the two DotNetNuke.dll files. If there's a size difference, odds are the previous developer made changes to DNN Core, which means that you will not be able to upgrade without some of your custom modules breaking.
Selecting the Correct Version
If the developer didn't modify DNN, then the next question is: What version of DNN do I want? More like what version of DNN do I want to stop at. It's suggested that you do incremental upgrades to get to whatever version you're targeting. As you upgrade, check out the site to see how much, and what broke.
Fixing What Broke
Typically, it's skins, custom modules, sometimes it's the user login that breaks. Keep an eye on the summary report after each upgrade.
Easiest way to fix some of these is to re-copy certain files over.
Custom modules, you're slightly out of luck.....that's going to take some coding to fix.
User login? If this breaks, once again, it's going to be a challenge to fix.
Hopefully, by some miracle, you've made it through. Congrats, have a pizza.