You need to look at the log files more carefully. It clearly states that there is a problem with /tmp and not the ibay.
"File(/tmp/phpg7XLAB) is not within the allowed path(s): "
By default, a web application is not allowed to write to the /tmp directory. Your application is trying to store (temporarly) the .jpg image in the /tmp directory to check, resize, create thumbnail, etc. You need to allow this to happen.
Once the web app does it's thing, it will then move the .jpg to the avatar directory.