I'm seeing some difficulties here, maybe you can explain them:
1) You're using a string variable here to replace itself with another string. The same result could be achieved much easier
sFileName = Bigimg.FileName.Replace(Bigimg.FileName.ToString(), news.NewsId.ToString()) + sExtension;
sFileName = news.NewsId.ToString() + sExtension;
2) Something called "BlockImagePath" should be a string already. So no need to ToString() it.
And using
Path.Combine[
^] can help path creation robustness.
string sPath1 = Path.Combine(
ConfigurationManager.AppSettings["BlockImagePath"],
sFileName
);
3) Delete something that isn't there?
if (!File.Exists(sPath1))
File.Delete(sPath1);
I suppose that you wanted that without the "
!".
4) And the you're saving an image to disk, read it again, and re-write it another time.
I think you should provide some insight in the data type of
PostedFile.