"except KeyError, e:" indicates that you are using python3 to run code that is only valid for python2. see https://github.com/weewx/weewx/wiki/faq-python-error
Upgrade your MQTT extension to a current version. -- You received this message because you are subscribed to the Google Groups "weewx-user" group. To unsubscribe from this group and stop receiving emails from it, send an email to weewx-user+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/weewx-user/2beac3b1-a0b4-4735-8943-5eb3f4a0e5d7n%40googlegroups.com.
