Error initializing block database. Do you want to rebuild the block database now? I'm trying to set up a test network consisting of 3 nodes, each with different bitcoin.conf. I've constructed the directory and the .conf-files similar to what is the state of the art in qa/pull-tester/.
Within the terminal inside the node-A-directory I commanded: ...

bitcoind -conf="/home/me/.bitcoin/regtest/testnetwork/A/bitcoin.conf"


...and got back this error:

'Error initializing block database. Do you want to rebuild the block database now?'

My bitcoin.conf has following content:

regtest=1
rpcuser=rt //adopted from .conf-files in qa/pull-tester/
rpcpassword=rt //adopted from .conf-files in qa/pull-tester/
port=11111 //arbitrary free port
rpcport=21111 //arbitrary free port


Could someone please help with my intended network setup or at least say what I'm doing wrong?

PS: I'm going to paste my logfile in a comment below.
As the question is already answered in the comments and there anothere question arouse about how to send API commands independently to the server from each node.

As Nick ODell gave a correct hint, in fact you need to prefix each API command like "getbalance" with "bitcoin-cli -conf="!

Thanks to Nick ODell!