DNN9 File Upload with <input type='file' /> - dotnetnuke

Question

On DNN 9.6, try to run a custom webform module (built originally on DNN 4.5)
I am trying to upload file
When first navigating to the page, the upload result is always with the postedfile = null
In header/request body, the Content-Type: application/x-www-form-urlencoded; charset=UTF-8
I can see in the request
__ASYNCPOST: true
If try to upload the second time, it will work and with heade/request
Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryfzAkNd7yEs3BGnG8
How to get it to full postback at the first time in DNN
<table id="tblUpload" runat="server" cellspacing="0" cellpadding="0">
<tr><td valign="bottom">
<dnn:label id="plPhoto" runat="server" suffix=":" controlname="lnkPreview"></dnn:label>
</td>
<td valign="top">
<input id="filePhoto" type="file" size="50" name="File1" runat="server" />
</td>
</tr>
<tr>
<td valign="bottom"><dnn:label id="plSaveAsFile" runat="server" suffix=":" controlname="txtFileName"></dnn:label></td>
<td>
<asp:textbox id="txtTitle" runat="server" Width="200px" MaxLength="200"></asp:textbox>
<asp:linkbutton CssClass="CommandButton" id="cmdUpload" runat="server" borderstyle="none" text="Upload" resourcekey="cmdUpload"></asp:linkbutton>
<asp:linkbutton class="CommandButton" id="cmdCancel2" runat="server" borderstyle="none" text="Cancel"
resourcekey="cmdCancel" causesvalidation="False"></asp:linkbutton>
</td>
</tr>
</table>

Answer 1

Inside of your manifest for your control, you will have something such as.
<supportsPartialRendering>true</supportsPartialRendering>
Changing this value to "false" is the fasted, and most reliable method to ensure that this is not done via an Async post. There are more advanced ways of doing it, but this is the easiest.