I have a problem inilizing my wallet.dat and found that the problem is with Core v0.21.0
Yesterday, after I received the last payment from nicehash, I open Bitcoin Core, but always while loading the same block, I think that the one in which the transfer from Nicehash is located, Bitcoin Core just closed without any error message.
After trying several times and reinitializing the wallet.dat, I installed v0.20.1 and the problem was solved ...