a problem of my bitcoin-core
Try to reload your bitcoin node by reinstalling, backup your wallet.dat to be sure you got that safe!

You can just uninstall the wallet without emptieng your data folder first, safes you some downloading. After that delete all files in the data directory except: blocks folder and wallet.dat.

Install bitcoin qt again and make sure you pick the right data directory again. Opening of the wallet will take a while due to checking of the blockchain and building the chainstate.

Probably your error is nog gone.