I ask for explanations and help.

Today I discovered that my wallet does not display the fresh coins that I bought on the exchange and sent to it (although the balance is reflected correctly in the explorer). I began to investigate this problem and was surprised to find that a new version 2.0.3 client was released in November, and I use version 1.0.0.0 (although I installed it in October). When I downloaded the new wallet and tried to replace the file wallet.dat with my old one, the new wallet did not start and reported that my file was corrupt! How can it be?! I have not seen anywhere on the forum announcements about the fork, the coin swap, the mandatory update, or even the replacement of the ticker! Why is this so ?! How can I launch my new wallet and not lose all my coins?

Fortunately, I solved my problem by importing a private key, so the question is canceled. But I still do not understand why there are no messages and announcements about this on the Bitcointalk forum.

P.S. tutorial https://www.youtube.com/watch?v=01BXlEhvOnc&feature=youtu.be