I have alredy looked at a lot of other similar questions here but they didn't involve my case or the solutions provided did not work for me. I'm trying to work in regtest mode and I'm using bitcoin core v0.15.0 on a Debian machine. My bitcoin.conf file looks like this:

$HOME/.bitcoin/bitcoin.conf ->
rpcuser=bitcoinrpc
rpcpassword=7bljxv........zabyi

I run the command

bitcoind -regtest -daemon

And then

bitcoin-cli -regtest getblockchaininfo

And it works fine, but if I try to run the following command:

bitcoin-cli -regtest generate 101

I get the following error:

error code: -32601
error message:
Method not found