ORA Database Error Messages ORA-06127: NETTCP: unable to change username July 8, 2015 mpbod ORA-06127: NETTCP: unable to change username Cause: The host’s SQL*Net TCP/IP server could not establish a PROXY LOGIN connection because the client username is unknown (to the host OS). Action: Create new user account on host. Back to previous menu https://support.oracle.com/ http://www.oracle.com/ Share this:Click to email a link to a friend (Opens in new window)Click to print (Opens in new window)Click to share on Facebook (Opens in new window)Click to share on LinkedIn (Opens in new window)Click to share on Tumblr (Opens in new window)Click to share on Twitter (Opens in new window)Click to share on Pinterest (Opens in new window)Click to share on Reddit (Opens in new window)Click to share on Pocket (Opens in new window)