sudo apt-get update && sudo apt-get dist-upgrade

as I said, your official repo is damn slow, it's not possible to update and all the other mirrors are outdated.

It was very easy for me, sorry it wasn't for you. What happened for me was, I saw that updates were ready, so I clicked on it. I was surprised it was for such a large file, but I let it do its thing and came back the next day and discovered that it had not updated, it actually had upgraded, from 15.2 to 15.3.

I agree that Deepin updates are slow, but the distro is so good IMO that it's worth it. 15.3 is really nice, very polished. It's working very well and is my go-to distro at this point.

lucky man

Go to backup /home and start a install clean for 15.3. I made it today, but I used Kali before; I like the Deepin system.

The problem remains identical:

For "some reason",  for some users, it is impossible to upgrade from 15.2. Knowing how easy it is for others doesn't help.

The strangest fact, to me, is that the day of 15.3 release, I indeed got an update... for a partial 15.2 upgrade!!!

The only one thing, I installed "by hand", was a calendar from KDE...

I have successfully updated to 15.3.. all the mirrors seems are being syncing..
cheers.