Error Method "OpenBinaryStream" does not exist SharePoint file download using CSOM C#

Question

we are using the below code to download a file from the SharePoint 2010 on-premise and from SharePoint online site. The code is working fine SharePoint online file and getting the error Method "OpenBinaryStream" does not exist for the SharePoint 2010 on-premise site. Can anyone help me to fix the issue?

 private static byte[] GetFileData(ClientContext clientContext, string SiteUrl, string path)
        {
            try
            {
                var web = clientContext.Web;
                clientContext.Load(web, website => website.ServerRelativeUrl);
                clientContext.ExecuteQuery();
                var regex = new Regex(SiteUrl, RegexOptions.IgnoreCase);
                var siteRelavtiveURL = regex.Replace(path, string.Empty);
                var serverRelativeURL = web.ServerRelativeUrl + siteRelavtiveURL;

                var file = web.GetFileByServerRelativeUrl(serverRelativeURL);
                clientContext.Load(file);
                clientContext.ExecuteQuery();
                var stream = file.OpenBinaryStream();
                clientContext.ExecuteQuery();

                using (var memoryStream = new MemoryStream())
                {
                    stream.Value.CopyTo(memoryStream);
                    return memoryStream.ToArray();
                }
            }
            catch (Exception ex)
            {
               
                return new byte[0];
            }           
        }

Answer 1

In SharePoint 2010 CSOM, try to get file stream using Microsoft.SharePoint.Client.File.OpenBinaryDirect, here is the modified code:

 private static byte[] GetFileData(ClientContext clientContext, string SiteUrl, string path)
        {
            try
            {
                var web = clientContext.Web;
                clientContext.Load(web, website => website.ServerRelativeUrl);
                clientContext.ExecuteQuery();
                var regex = new Regex(SiteUrl, RegexOptions.IgnoreCase);
                var siteRelavtiveURL = regex.Replace(path, string.Empty);
                var serverRelativeURL = web.ServerRelativeUrl + siteRelavtiveURL;

                var file = web.GetFileByServerRelativeUrl(serverRelativeURL);
                clientContext.Load(file);
                clientContext.ExecuteQuery();
                FileInformation fileInfo = Microsoft.SharePoint.Client.File.OpenBinaryDirect(clientContext, serverRelativeURL);
               
                //var stream = file.OpenBinaryStream();
                //clientContext.ExecuteQuery();

                using (var memoryStream = new MemoryStream())
                {
                    fileInfo.Stream.CopyTo(memoryStream);
                    return memoryStream.ToArray();
                }
            }
            catch (Exception ex)
            {

                return new byte[0];
            }
        }

Reference:

Method “OpenBinaryStream” does not exist reading a file from SharePoint 2010