Our app worked fine with Version 1 and Version 2 of the Regulations.gov API, but I can't get it to work with version 3. I am using a new API key, and pasting the complete URL in the browser brings back good data. However, when used in our program it returns a "(406) Not Acceptable" error. I also used my new API key in the "Try it now" section on this site, and it also returns an error. It doesn't seem to make sense when pasting the URL in the browser seems to work fine.
Use a network sniffer like Wireshark to compare:
- The request that fails
- The request that succeeds
There is probably a tiny difference in the request, that you can find out and fix.
Network sniffers are easier to use on HTTP, but if you are forced to use HTTPS, there are still various solutions.