protocol integration error code 15 when tring to login

I use DemoApp sample from SDK it was working fine with no error and suddenly when I found error code 15 when trying to login

In the MIP Documentation in Mobile server protocol - Appendix there is a list of Command error codes. In the list is

15 = Incorrect user password

A first troubleshooting is to check the user that logs in. If you use the same user in the Webclient does it work?

yes, its working fine in webclient.

thank you I think the issue was that I have \ in my password.