Message Oracle PGA-22007 - user ID string length of number is invalid; maximum length is number

ERROR	user ID string length of number is invalid; maximum length is number
CAUSE	The user id is too long to be used. The maximum allowable length for the user ID is characters.
ACTION	The user id must be changed to a shorter value for OCI logon to the table PGA_TCP_IMSC. Refer to the Oracle Database Gateway Installation and Configuration Guide for the required gateway initialization parameters for gateways using TCP/IP.