It is failing on prosody 0.11.4 with mod_limits_exception.lua:29: attempt to call method 'set_stanza_size_limit' (a nil value). That prosody misses set_stanza_size_limit.
In case limited those connection will be whitelisted and unlimited. Updates existing configurations to make sure prosody update will not break it by limiting too much.
Uses 28c16c93d79a version of the module: https://modules.prosody.im/mod_limits_exception.html
Will be available in prosody 0.12.