主题：[追问]远程升级，如何避免升级文件不存在时的报错

远程升级，如何避免升级文件不存在时的报错？

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远程服务器返回错误: (404) 未找到。
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确定  
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先检测

Dim url As String = "http://www.foxtable.com/download/release.rar"
try
    Dim rqst As System.Net.HttpWebRequest = System.Net.HttpWebRequest.Create(url)
    Dim rsps As System.Net.HttpWebResponse = rqst.GetResponse
catch ex As Exception
    msgbox(ex.message)
End try

FTP检测时提示：  超时！      

Dim url As String = "ftp://zyqaa:Hxl2126705@192.168.137.246:21/Update/update.txt"  
        try
            Dim rqst As System.Net.FtpWebRequest = System.Net.FtpWebRequest.Create(url)
            Dim rsps As System.Net.ftpWebResponse = rqst.GetResponse
        catch ex As Exception
            msgbox(ex.message)
        End try

FtpWebRequest类也有同样的方法，为什么不行呢？

上面这句如何用？

改为如下的写法，还是不行？

        try
            Dim rqst As System.Net.FtpWebRequest = System.Net.FtpWebRequest.Create(url)
            Dim rsps As System.Net.WebResponse = rqst.GetResponse
        catch ex As Exception
            message =  ex.message
        End try

ftp就直接用ftpclient去测试连接和判断就好啊

http://www.foxtable.com/help/topics/1410.htm