I try to get and api from odk aggregate using this :
GET /view/downloadSubmission?formId=my_odk_form[@version=null and @uiVersion=null]/data[@key=uuid:38fd4ef4-28b9-441e-a818-dd8cbe514b2c]
@Dimas_Djs You are correct that you've probably got the wrong (or rather improperly encoded) URL. Whatever programming language you are using to send that request to Aggregate has a way to url encode the URL before you send it.