Re: Please help me with the issue of unlocking bitcoin core wallet.
Hmm, that's odd.
If that was the issue, you shouldn't be getting the "method not found (code-32601)" error; instead, it should be returning 'help' for walletpassphrase command if there's a 'space' in your password or a 'blank error message' / 'invalid command line' if there's an invalid character when you didn't add the quotation marks.
Given the OPs location and comments, it is possibly related to the use of non-Latin characters (ie. Chinese) in the passphrase... and the way that the system is parsing it... TBH, I'm not surprised it might be something as simple as using ' instead of "...If that was the issue, you shouldn't be getting the "method not found (code-32601)" error; instead, it should be returning 'help' for walletpassphrase command if there's a 'space' in your password or a 'blank error message' / 'invalid command line' if there's an invalid character when you didn't add the quotation marks.
I've had a bugger of a time with Bitcoin Core parsing JSON because of similar ' vs " issues
