Started getting a deployment error.  Checked IIS server event viewer and saw an user audit failure - "an account to failed to log on."

It listed the account i use via webdeploy as the 'account name'

HOWEVER, below that it lists "account for which logon failed" and that account is the wdeployconfigwriter account. so the account it listed first was fine, it was the wdeployconfigwriter account that had the logon problem.

windows by default will set this account to expire after so many days.  This is not an account that is used to logon with, so no notification was given that it was expiring.

updated things on the server around those accounts and the web deployment worked again.  It really sucks that the webdeploy bits don't provide better info (user id password IS expriring and HAS expired).  Probably issue with the MS webdeploy, not sure if appeon can do anything about that.

Reference:  

iis 7 - Webdeploy Issues: Cannot deploy unless admin - Stack Overflow