Can someone please help me?timeout on transient error: Could not connect to the server 127.0.0.1:8332

I use CENTOS to test
cert-issuer, I use vi /root/.bitcoin/bitcoin.conf, add fallbackfee=0.00001 in bitcoin.conf and save it, execute bitcoind -daemon=/root/.bitcoin/bitcoin.conf, use bitcoin-cli sendtoaddress $ Issuer 5 command, but get the following error message
error: timeout on transient error: Could not connect to the server 127.0.0.1:8332

Make sure the bitcoind server is running and that you are connecting to the correct RPC port.

Can someone please help me? My TCP:8332 has been turned on