Oracle Message O2I-00101 - Invalid value for the USERID parameter

ERROR	Invalid value for the USERID parameter
CAUSE	The value supplied for the USERID parameter is not a legal /[@] string.
ACTION	Set the USERID option to the correct / or /@ combination to use when connecting to the database. If you have an OPS$ account, you may instead omit the USERID option, in which case OTT will attempt to connect to the database using the userid OPS$. The USERID option may be specified on the command line or in a CONFIG file.