how to notify a user by jabber in workflow ?

Workflow only generates a letter, but the user itself decides the notifications ways on his profile.

that's not enough.
i had workflow to change status from open to fixed. but the user won't be notified by jabber. no matter the reporter or the assignnee.
you should imply this feature to user workflow to send jabber message.

Please clarify the problem. Can workflow sent notification to user by the email or jabber?

Please check that
- global email/jabber settings are configured properly
- user enabled email and/or jabber notifications

Also please note that with standard settings workflow which runs by the logged in user won't sent notification to this logged in user because it's author of the current change.

i'm using your workflow "jetbrains-youtrack-notifyReporterToApproFix
You can try that, there is no jabber notification sent to the reporter, only the email.

my jabber settings are all enabled and working for other status changs such as open to fixed

Thank you for the feedback, it looks like a bug. I created the issue JT-21505.