Reasons for a 409/Conflict HTTP error when uploading a file to sharepoint using a .NET WebRequest?

Since no answers were posted, I found the following here:

The Web server (running the Web site) thinks that the request submitted by the client (e.g. your Web browser or our CheckUpDown robot) can not be completed because it conflicts with some rule already established. For example, you may get a 409 error if you try to upload a file to the Web server which is older than the one already there - resulting in a version control conflict.

Someone on a similar question right here on stackoverflow, said the answer was:

I've had this issue when I was referencing the url of the document library and not the destination file itself.

i.e. try http://server name/document library name/new file name.doc

However I am 100% sure this was not my case, since I checked the WebRequest's URI property several times and the URI was complete with filename, and all the folders in the path existed on the sharepoint site.

Anyways, I hope this helps someone.

I found 2 things worth mentioning while uploading files using webdav and http web request. First, for the provider I was using, I had to append the filename at the end of the provider url. Ihad to append the port number in the url. And I also set the Request method to PUT instead of POST.

example:

string webdavUrl = "https://localhost:443/downloads/test.pdf";
request.Method = "PUT";

We are also getting the same error while we are trying to access a same resource with in milliseconds. Like if i try to POST some data to www.abc.com/blog and with in milliseconds an other request will also go for the same resource i.e. www.abc.com/blog from the same user. So it'll give the 409 error.