Based from the hint above, do you somehow have a disablewallet=1 entry in your bitcoin.conf file or as an additional start parameter in your shortcut?
Because disabling the wallet will make 'wallet RPC commands' like walletpassphrase disabled.
After I downloaded the Bitcoin core wallet, no other operations have been performed. If I disable it, how can I find out? Then how to unban it? I'm a novice, please!
The most noticeable one is the GUI, there will be no wallet UI, just the 'Console', 'Information', 'Peer' and 'Network traffic' tabs.
To re-enable the wallet (
if disablewallet is the culprit):
Check your Bitcoin data directory (
location) if there's a "
bitcoin.conf" file inside it, if there is, open it using a text editor and check if there's a
disablewallet=1 line.
For a possible added start parameter, if you're on Windows and running using a shortcut, check its properties and look for
-disablewallet at the end of the Target, if there is, remove it.
Thank you very much for your help, I have found the problem, and I will try my best to help others in the future!