Upgrade from 4.0 to 4.4

Dear Community,
how shall I upgrade the compltete page from 4.0 to 4.4. In the description it says:
Remove all files from the previous version except JSON files in the 'App_Data' directory such as dataSettings.json (Settings.txt in oldest versions), plugins.json (InstalledPlugins.txt in oldest versions), appsettings.json, move them to the safe place.

But what about style sheets, themes, changes in the source code in various projects through the whole solution ?
We did a lot of changes in the source code how to migrate them ? Do we have to do all of this manually ?

What about all the plugins and customizations there?

Any ideas and hints would be appreciated. THX

dccwebteam wrote:Get the latest version of the Theme for v4.4

dccwebteam wrote:Get the latest version of the Plugin for v4.4

dccwebteam wrote:Yes.
You can check if the changes have allready been added as updates over the versions
Or look at the market place for plugins that may now do what you need
Otherwise you can use a compare tool to compare your version and the Standard Versions. Then add the changes.