If you received this error it is because your txid is invalid.
To verify that your TXID and Output Index are correct, open the debug console of your wallet and type the command:
The list of valid TXIDs for masternodes will be shown. The first column is the TXID and the second column is the Output Index.
If your TXID does not appear in the list your masternode will not start, in which case you should create a new TXID:
Delete the line of the masternode you want to create the new TXID from masternode.conf file
If your txid appears in the list make sure it is configured correctly on the system: