How to import wallet.dat into 3.0.X.X?

[einalex]

this comment explains how to use that

I cannot initialize my masternode

At the moment, the “initialize” button has a bug. You will need to use the console. To do that Click on “Window->Console” Unlock your wallet by entering walletpassphrase [PASSPHRASE] [SECONDS] replace [PASSPHRASE] with your passphrase replace [SECONDS] by the number of seconds after which you want the client to lock the wallet again. Initialize your masternode by entering masternode initialize [LABEL] replace [LABEL] with the name of the masternode you want to restart. Lock your wal…

help walletpassphrase will provide even more information.