I asked this question on AskUbuntu and was told to post it here.
I am trying to follow the Mastering Bitcoin tutorial. After compiling Bitcoin Core, and changing the datadir to my external hard drive in the config file, I get the following error any time I try a Bitcoin-cli command:
error: Could not locate RPC credentials. No authentication cookie could be found, and RPC password is not set. See -rpcpassword and -stdinrpcpass. Configuration file: (/media/XXXX/f1ebcea0-6304-4580-9ce2-1416dc0be49f/BlockchainData/bitcoin.conf)
When I search the forums, the only solution to this error is that Bitcoind was not running, but I confirmed that it is running. I suspect it has something to do with my hard drive permissions or admin level, but everything seems to be set up properly.