I've read through the blog post about OAuth 404 errors several times, but I can't quite get authorization to work. Since I'm developing on a workstation behind NAT, I was using

External URL: http://localhost/
External Domain: localhost/

An OAuth request with oauth_callback=http://localhost/myspace or the like always fails with "404 - Bad Request - ApplicationDomain or Callback Uri not set."

I tried localhost, http://localhost, and http://localhost/ with no successs. Thinking that a TLD was needed, I tried to use the access delegation tool. Using the default callback uri of the delegation tool itself, I tried every combination of myspace.com and developer.myspace.com for the external domain, with http:// and without, but every request fails with the same error after clicking "Yes, Link this Account."

 Any help would be greatly appreciated.

Now this is strage; at the moment every time I go back to the Edit App page currently all the details except the name are reset to the defaults -- this includes Installable being set off, Use External URL, and the URL & Domain. This may or may not be related to my problem above, but it does make it difficult to confirm any settings.