Hi!
Could you check the following settings in your site web.config:
<system.web>
<httpModules>
<add type="DevExpress.Web.ASPxClasses.ASPxHttpHandlerModule, DevExpress.Web.v9.1, Version=9.1.4.0, Culture=neutral, PublicKeyToken=b88d1754d700e49a" name="ASPxHttpHandlerModule" />
</httpModules>
<httpHandlers>
<add type="DevExpress.Web.ASPxUploadControl.ASPxUploadProgressHttpHandler, DevExpress.Web.v9.1, Version=9.1.4.0, Culture=neutral, PublicKeyToken=b88d1754d700e49a"
verb="GET" path="ASPxUploadProgressHandlerPage.ashx" validate="false" />
</httpHandlers>
</system.web>
<system.webServer>
<security>
<requestFiltering>
<requestLimits maxAllowedContentLength="2097151000" />
</requestFiltering>
</security>
<validation validateIntegratedModeConfiguration="false" />
<modules>
<add type="DevExpress.Web.ASPxClasses.ASPxHttpHandlerModule, DevExpress.Web.v9.1, Version=9.1.4.0, Culture=neutral, PublicKeyToken=b88d1754d700e49a" name="ASPxHttpHandlerModule" />
</modules>
<handlers>
<add type="DevExpress.Web.ASPxUploadControl.ASPxUploadProgressHttpHandler, DevExpress.Web.v9.1, Version=9.1.4.0, Culture=neutral, PublicKeyToken=b88d1754d700e49a" verb="GET"
path="ASPxUploadProgressHandlerPage.ashx" name="ASPxUploadProgressHandler" preCondition="integratedMode" />
</handlers>
</system.webServer>
These settings are necessary to make the progress bar work correctly when uploading a file.