回发后下载出现PageRequestManagerParserErrorException异常求助

Ah, I’ve run into this exact issue before! The problem happens because the UpdatePanel uses AJAX partial postbacks, which expect a specific JSON/XML response from the server. When you try to send a file download response (binary or non-standard content type), the AJAX framework can’t parse it—hence the PageRequestManagerParserErrorException.

Here are two reliable solutions to fix this:

Solution 1: Register the LinkButton as a Full Postback Control #

Since your LinkButton is inside a Repeater, we can’t declaratively add it as a trigger to the UpdatePanel. Instead, we’ll programmatically register it to trigger a full postback using the ScriptManager.

Step 1: Handle the Repeater’s ItemDataBound Event #

In your code-behind, add this event handler for the rptInfo Repeater:

protected void rptInfo_ItemDataBound(object sender, RepeaterItemEventArgs e)
{
    // Check if we're dealing with a data item
    if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
    {
        // Find the LinkButton in the current item
        LinkButton lnkSaveInfo = e.Item.FindControl("lnkSaveInfo") as LinkButton;
        if (lnkSaveInfo != null)
        {
            // Register the button to trigger a full postback
            ScriptManager.GetCurrent(Page).RegisterPostBackControl(lnkSaveInfo);
        }
    }
}

Don’t forget to wire up the event in your ascx:

<asp:Repeater ID="rptInfo" runat="server" OnItemDataBound="rptInfo_ItemDataBound">

Step 2: Properly Send the Download Response #

In your LinkButton’s command handler (since you’re using CommandName="saveInfo"), make sure to clear the response and end it after sending the file:

protected void lnkSaveInfo_Command(object sender, CommandEventArgs e)
{
    if (e.CommandName == "saveInfo")
    {
        // Replace with your logic to get the file data and name
        byte[] fileContent = GetFileContent(); // Your method to fetch the file
        string fileName = "your-document.pdf";

        // Clear any existing response content
        Response.Clear();
        Response.ContentType = "application/pdf"; // Adjust based on your file type
        Response.AddHeader("Content-Disposition", $"attachment; filename=\"{fileName}\"");
        Response.BinaryWrite(fileContent);
        Response.Flush();
        Response.End(); // Critical to stop further page processing
    }
}

Wire up the Command event in the Repeater’s ItemTemplate:

<asp:LinkButton runat="server" ID="lnkSaveInfo" CommandName="saveInfo" OnCommand="lnkSaveInfo_Command" />

Solution 2: Use a Hidden Button Outside the UpdatePanel #

If you prefer not to modify the postback behavior of the LinkButton directly, you can use a hidden button outside the UpdatePanel to trigger the download via JavaScript.

Step 1: Add a Hidden Button and Hidden Field (if needed) #

Add these controls outside your UpdatePanel:

<asp:Button ID="btnHiddenDownload" runat="server" Text="" Style="display: none;" OnClick="btnHiddenDownload_Click" />
<asp:HiddenField ID="hfFileIdentifier" runat="server" /> <!-- To pass file-specific data -->

Step 2: Modify the LinkButton to Trigger JavaScript #

Update your Repeater’s LinkButton to call a JS function instead of a direct postback:

<asp:LinkButton runat="server" ID="lnkSaveInfo" 
    OnClientClick="prepareDownload('<%# Eval("FileId") %>'); return false;" />

Step 3: Add the JavaScript Function #

Add this script to your ascx:

function prepareDownload(fileId) {
    // Set the file ID in the hidden field so the server knows which file to send
    document.getElementById('<%= hfFileIdentifier.ClientID %>').value = fileId;
    // Trigger the hidden button's click (full postback)
    document.getElementById('<%= btnHiddenDownload.ClientID %>').click();
}

Step 4: Implement the Hidden Button’s Click Handler #

In code-behind, handle the hidden button’s click to send the download:

protected void btnHiddenDownload_Click(object sender, EventArgs e)
{
    string fileId = hfFileIdentifier.Value;
    byte[] fileContent = GetFileContentById(fileId); // Your method to fetch the file
    string fileName = $"document-{fileId}.pdf";

    Response.Clear();
    Response.ContentType = "application/pdf";
    Response.AddHeader("Content-Disposition", $"attachment; filename=\"{fileName}\"");
    Response.BinaryWrite(fileContent);
    Response.Flush();
    Response.End();
}

Key Notes #

• Always use Response.Clear() and Response.End() when sending download responses to ensure no extra content is sent back to the AJAX framework.
• If you’re using other file types, adjust the ContentType accordingly (e.g., text/csv for CSV files, image/png for PNGs).

内容的提问来源于stack exchange，提问作者Ali Soltani