Sunday, December 13, 2009

FCKeditor with ASP.NET. File uploads. Making them work in IE7 and Chrome.

FCKeditor, now known as CKEditor, presumably because the original sounded too risqué, is quite a popular open-source rich text editor for use in web pages. I've used it in quite a few projects and always been pretty happy.

Although the current release is CKEditor 3.0.1, ASP.NET developers are still using FCKeditor 2.6.5, since there isn't any ASP.NET integration in CKEditor 3 yet. And it was with 2.6.5 that I ran into a puzzling problem with file uploads.

File uploading is disabled by default, but if you need to, you can enable it, and allow people editing text to upload files and link to the resulting upload. I'd only tried it once before, for a project that never went ahead and thus never left our test server, and it worked fine there.

However, this time, once it was up on an external staging server.. the upload only worked with Firefox. With IE7 and Chrome, I'd hit the "Send it to the Server" button, and the progress indicator would spin forever, achieving nothing.

So I dug a bit. Was the file being successfully uploaded? Yes, it was. Was an error being returned by the Ajax call? I inspected it with Fiddler and it looked OK - no error, a 200 response code sending back a chunk of Javascript to the browser. So obviously there was something wrong with the Javascript.

Having narrowed it down to this bit of Javascript, and identified that it was being emitted by the function FileWorkerBase::SendFileUploadResponse() in the FCKeditor.NET library, I was able to Google with more confidence, and a solution was found at

Basically there is something going wrong with the Javascript's attempts to fiddle with document.domain. Removing is, as per that ticket, fixed the problem.

  1. Download the FCKeditor.NET library source from

  2. Open up FileBrowser/FileWorkerBase.cs

  3. Replace the SendFileUploadResponse(int errorNumber, bool isQuickUpload, string fileUrl, string fileName, string customMsg) function on line 110 with the version from

  4. Rebuild and replace your FredCK.FCKeditorV2.dll !