RPC call for disabled connector, no such connector

Vaadin 6 / 7 / 8
1

When my application publish to the server ,server logs display many warnings such as (the client brower is IE8):
Ignoring RPC call for disabled connector com.vaadin.ui.Button
Ignoring RPC call for disabled connector com.vaadin.ui.ComboBox
RPC call to v.v received for connector 30 but no such connector could be found. Resynchronizing client.
RPC call to com.vaadin.shared.ui.button.ButtonServerRpc.click received for connector 227 but no such connector could be found. Resynchronizing client.

What’s happened in my application?

2

and when happen these warnings ,the page will refresh,and all inputfield content clear!

3

no answer?