How to overwrite an existing document in SharePoint Library with a new document with different name?

Name the file you want to upload doc1.pdf. Go to "Upload" like you are adding a new file to the SharePoint folder. However, make sure the checkbox is selected "Add as a new version to existing files". This will overwrite the current doc1.pdf but keep your versioning.

I know this is not quite an answer you may be looking for, but why not rename doc2.pdf to doc1.pdf and then rename it in SharePoint itself?

To avoid getting rid of data associated with the original file, you can open the file in "Open in Windows Explorer", then you can overwrite the file there. With a PDF, it maintains the ancillary information. CAUTION: It does NOT maintain with .doc files (which is annoying).

You can use the below code to update file content of existing file with new content and file name.

static void ReplaceFileContentWithNewFile(ClientContext context, string sourceLibraryName, int itemId, string newFilePath, string newFileName) {

 List sourceLibrary = context.Web.Lists.GetByTitle(sourceLibraryName); ListItem item = sourceLibrary.GetItemById(itemId); Microsoft.SharePoint.Client.File file = item.File; context.Load(item, i => i.File); context.ExecuteQuery(); using (FileStream fs = new FileStream(newFilePath, FileMode.Open, FileAccess.Read)) { var fileCreationInfo = new FileCreationInformation { ContentStream = fs, Url = file.ServerRelativeUrl, Overwrite = true }; Microsoft.SharePoint.Client.File uploadFile = context.Web.RootFolder.Files.Add(fileCreationInfo); context.Load(item); context.ExecuteQuery(); } string newFileUrl = file.ServerRelativeUrl.Replace(file.Name, newFileName); file.MoveTo(newFileUrl, MoveOperations.Overwrite); context.ExecuteQuery(); 

}