I'm running a query on the url http://api.createsend.com/api/v3/lists/(mylistid)/customfields/Source/options.json
(mylistid) is the listID for a list which has a custom field called "Source".
but I'm getting a 404....
Just FYI source, [Source], and [source] all return 404 too.
Any ideas what I'm doing wrong?
Use PUT instead of POST
Yes, we try to use HTTP verbs meaningfully in our API, and the use of PUT for updating custom field options is documented here. Glad you figured it out.