401 Unauthorized on auth_user

[Kevin]

I am getting a 401 unauthorized exception when I call the auth_user api. I have the access token and token_secret, and I am able to successfully call other apis that require oauth such as freind/request.xml. I am using C# - here is what the header looks like on the call to auth_user:

GET /api/auth_user HTTP/1.1
Content-Type: application/x-www-form-urlencoded
Authorization: OAuth oauth_callback="oob", oauth_consumer_key="xxxxxxxxxxxxxxxxxx", oauth_nonce="vz784t07", oauth_signature="t6FHAP5%2B%2F1um5jYrtVAu0S3Z09M%3D", oauth_signature_method="HMAC-SHA1", oauth_timestamp="1455212773", oauth_token="B2OGM2rCK6F9XB8mXYQ2w", oauth_version="1.0"
Host: www.goodreads.com
Accept-Encoding: gzip
Connection: Keep-Alive

Any help is appreciated.

[Kevin]

I'm going to try asking this in a different way - if anyone is successfully using the auth_user api call, would you mind using fiddler or something to record the header and body of the http request and posting it here (remove your secrets). I would be very grateful!

[Daniel]

I don't have the time to record it now, but the Swift example I posted here (https://www.goodreads.com/topic/show/...) calls oauth_user successfully, and from what I recall the header looks pretty much the same as yours, except it doesn't include Accept-Encoding and Connection. Also I compared my signature base string to this (http://oauth.googlecode.com/svn/code/...) and it helped me fix some issues.