Posted as a reply to a different thread, but I figured others may be having issues efiling with the 2024 FX module.

There are many technical changes for the 2024 filing year - please check all the following:

 1) Under EFILE -> Options -> T3/FX -> Transmitter:

     - Ensure Transmitter Name does not include any non-alpha characters (we had to remove a "." and also replaced "&" with "and");

     - Ensure Rep ID and Transmitter Numbers (Business number + Web Access Code) are filled in

2) Under EFILE -> Options -> T3/FX -> Contact information:

     - Ensure both contacts are filled in, including an email address

3) Under Options -> Environment -> Preparer, ensure RepID is filled in (matching with EFILE options above)

4) Slip Recipient names CANNOT be longer than 30 characters - this will restrict filing. In previous years, you could file despite the error message, but this is no longer allowed.

5) When you get the message "503.0 This service has moved" in the efiling window, click "File information returns electronically (tax slips and summaries), then "How to file," then "Internet file transfer." You can then proceed with filing as in previous years.

My understanding is that CRA changed their XML format for 2024, which is the cause of issues #1 through #4. Hopefully, Profile is working to fix issue #5....

I hope this helps!