请教一个问题！关于tabs.sendMessage

[zhurizhe]

我在background里使用tabs.query获取tab，然后sendMessage，为什么会返回下面这个错误？
Unchecked runtime.lastError: Could not establish connection. Receiving end does not exist.

 chrome.tabs.query({currentWindow:true},function(tabs){
        for(let i in tabs){
            chrome.tabs.sendMessage(tabs[i].id, {greeting: "hello"}, function(response) {
                console.log(response.farewell);
              });
        }
    })