I spent a lot of time installing several extensions and third-party applications from the software centre in ubuntu to customize the look and feel of the os.
Also, I have a lot of Softwares installed like PyCharm and sublime text and vscode. All of these are again customized. I can, of course, do all the customizations again, but it would consume a significant amount of time.
I wanted to know if all of these Softwares will get erased/removed after I perform the upgrade.
I'm using this command to bring up the update manager dialogue which would then prompt me to proceed with the update.
update-manager -c
Also, will this command make sure I keep all the installed Softwares even after the upgrade?
RELEASE_UPGRADER_ALLOW_THIRD_PARTY=1 update-manager -c
I will only proceed with the upgrade if I'm sure all the applications will remain intact after the upgrade, otherwise, I'm perfectly happy with using Ubuntu 18.04.
According to this answer, the already installed apps should not get damaged by the update. Does this answer still hold for 18.04 to 20.04?
Immediately after Ubuntu 18.04 was released I created a chatroom where Ask Ubuntu users could report applications from the default Ubuntu repositories that were removed from the official 16.04 repositories in Ubuntu 18.04. The total reported missing applications that had been removed from the default repositories in Ubuntu 18.04 was not more than 10 applications. I interpret this as evidence that you should have few problems with removed applications when upgrading from 18.04 to 20.04.
When upgrading from 16.04 to 18.04 I also found that a few applications that could not be upgraded were still installed and I could still open them, but some of them had to be removed because they didn't work properly in Ubuntu 18.04. Afterwards I searched for replacements and discovered reasons why some of these applications were removed from the default Ubuntu repositories. It was because new alternative applications were added to the Ubuntu 18.04 repositories that were better than the old ones. I strongly recommend that you don't give up if one of your favorite applications was removed from the default Ubuntu 20.04 repositories until you search in Ubuntu Software to check if there is a better replacement for it. You may be pleasantly surprised at the results!
Regarding PyCharm, Sublime text editor and Visual Studio Code I have all three of them currently installed in Ubuntu 18.04 which was fresh installed on a new computer. Before installing Ubuntu 18.04 I saved a list of all my existing extensions in PyCharm, Sublime and VSCode in a text file so that I could quickly reinstall them later.
Regarding third-party applications the release upgrade process is conservative and doesn't remove them, although I prefer to resolve possible compatibility issues by reinstalling all of them after upgrading. Before reinstalling any third-party applications I search in Ubuntu Software to check if there are any new applications in the latest release that I might like better.