When you do the connection test in transaction code SM59 – The connection test is failing with below error,
Incomplete logon data
Solution
There are multiple causes of this, you can check on below articles to tackle the problem.
SM59: User password invalid for identifier /RFC/ (see long text)
Below articles was specifically occurred on STMS RFC connection but you can refer to the steps based on the error.
STMS: RFC error when sending logon data
STMS: Error during the retieval of logon data stored in secure storage
