Troubleshooting XNAT Desktop Uploader

Symptom

Your uploads in the XNAT Desktop Client appear stuck. The progress bar does not move, and the uploaded session never appears in CNDA.

Step 1 – Confirm You Can Log In to CNDA

  1. Open your browser and go to https://cnda.wustl.eduopen in new window.
  2. Sign in using the same username and password used in XNAT Desktop Client.
  3. If login works → proceed to Step 2.
  4. If login fails → reset or confirm your CNDA password first.

Step 2 – Check that the Client Loads Configurations

  1. Open XNAT Desktop Client.

  2. Confirm that you can:

    • Log in successfully
    • View your list of projects
    • See configuration options load without errors
    • Reach the upload screen, even if the progress bar is stuck

  3. The server address must be exactly:

    cnda.wustl.edu

    There should be nothing after .edu (no slashes or sub-URLs).

  4. If you can browse projects normally → proceed to Step 3.

  5. If you get connection errors → check your internet or VPN and ensure you’re targeting the correct URL.

Step 3 – Verify the Upload Actually Starts

One way to verify if your process has reached the beginning of uploading is to check if an empty Subject was made on the CNDA website.

  1. Open your browser and go to https://cnda.wustl.eduopen in new window.
  2. Sign in using the same username and password used in XNAT Desktop Client.
  3. Search for your project in the top right and open it.
  4. If your XNAT Desktop app upload included making a new Subject, the new Subject should be visible with nothing in it.
  5. If the new Subject is visible, that means you got to the point where the uploading should begin, via POST request.
  6. But your uploading is stuck, so you don't see anything in the Subject.

If an upload never progresses past the loading screen, your computer may not be able to send POST requests (used for file transfers). You can test this easily in the next step.

Step 4 – Test POST Requests

  1. Press ⊞ Win + R → type cmd → press Enter.

  2. In the Command Prompt window, type:

    curl -X POST -u yourusername https://cnda.wustl.edu/data/JSESSION

  3. Enter your CNDA password when prompted (password input is invisible).

  4. Press Enter.

  5. Results:

    • If you receive a response containing a JSESSIONID → POST works → go to Step 5.
    • If you get a network or permission error → POST requests are being blocked → skip to Step 7.

Identifying POST Request Blocking

When testing POST requests using the following command:

curl -X POST -u yourusername https://cnda.wustl.edu/data/JSESSION

certain error messages may indicate that your institution or network is blocking outbound POST traffic.

Common error patterns:

  • curl: (7) Failed to connect to cnda.wustl.edu port 443: Connection timed out – The network is dropping or filtering HTTPS POST packets.
  • curl: (7) Couldn't connect to server – The firewall is blocking the outbound connection.
  • curl: (35) SSL connect error – HTTPS handshake failed due to SSL inspection or proxy interference.
  • curl: (56) Recv failure: Connection was reset – The request was terminated mid-transfer, often by a content filter.
  • curl: (60) SSL certificate problem: unable to get local issuer certificate – A proxy has replaced CNDA’s certificate, indicating SSL inspection.
  • curl: (22) The requested URL returned error: 403 Forbidden – The proxy or gateway is explicitly rejecting POST requests.
  • HTML error page (e.g., “Access Denied” or “403 Forbidden”) – A web security gateway returned a blocked-request page instead of JSON, confirming POST blocking.

Normal (working) response:

{"JSESSIONID":"ABC1234567890XYZ"}

Step 5 – If POST Requests Work, Clear Cached Data

  1. Press ⊞ Win + R → type %AppData% → press Enter.

  2. Open the Roaming folder

  3. Delete the folder named XNAT Desktop Client which is located inside of the Roaming folder.

  4. Completely Close and Restart XNAT Desktop Uploader.

  5. On the home screen, remove any saved server connections by clicking on the connection and then Remove in the pop up window.

  6. Click Add New XNAT Server and enter:

    cnda.wustl.edu

  7. Log in again.

  8. (Optional) Click the blue Home button at the top left and click → Flush XNAT User Access Cache.

  9. Retry your upload.

    • If uploads now work → problem solved.
    • If not → continue to Step 6.

Step 6 – Confirm the CNDA Certificate is Valid

  1. Open https://cnda.wustl.eduopen in new window in a browser.

  2. Do NOT log in yet.

  3. Click the padlock 🔒 or button right to the left of website url → Connection is Secure or View Certificate.

  4. Depending on your browser, here you may need to click on something that looks like a certificate or Certificate is Valid

  5. It should say:

    • Valid and Trusted
    • Issued to: InCommon RSA Server CA 2

  6. Log in to CNDA now and after login check the lock/certificate again.

    • If certificate stays the same → that is good, skip ahead.
    • If certificate changes after login → contact IT to whitelist cnda.wustl.edu so its certificate is not replaced by that of your institution.

Step 7 – If POST Requests Fail Everywhere

If the curl POST test fails, your network firewall is blocking POST traffic. Contact your institutional IT team and provide this message:

“Outbound HTTPS POST requests to https://cnda.wustl.edu are being blocked. Please whitelist this endpoint so uploads from XNAT Desktop Client can succeed.”

Final Notes

  • Always connect to exactly:

    cnda.wustl.edu

  • The most common fix: delete the XNAT Desktop Client folder under %AppData%\Roaming.

  • If that doesn’t help, it’s almost always a network POST blocking issue.

  • Once POST requests are allowed, uploads typically resume immediately.