Import/Export wallet vi bitcoin-cli. Bitcoin abc node I'd like move my bitcoin cash wallet from one server to the other using the cli. 

Server 1: bitcoin abc: 0.17.2.
Server 2: bitcoin abc: 0.18.0

I have done the following:


ran the command: backupwwallet "myfile.dat" on server 1 successfully. 
copy the "myfile.dat" to server 2.
rand the command: importwallet "myfile.dat".


I get the following the error when trying to import the wallet:

error code: -8
error message:
Cannot open wallet dump file.


I have also tried to replace stop the node on server 2 and copy the wallet.dat over to the other server and then start the wallet up again on server 2. 
I get the following error in the logs:

CDBEnv::Open: LogDir=/home/cryptodaemon/.bitcoincash/database ErrorFile=/home/cryptodaemon/.bitcoincash/db.log
2018-09-09 07:48:21 Failed to rename wallet.dat to wallet.dat.1536479301.bak


How can I move the wallet from one server to another?
Could anyone give me pointers in doing this?
importwallet is the opposite RPC of dumpwallet, not backupwallet.

backupwallet creates a copy of your wallet.dat file. You restore that file by putting it back in the data directory.

dumpwallet creates a wallet dump (just private keys, no history, addresses, labels, accounts, ...), which can be imported into an existing wallet using importwallet.