Why might a 404 error occur?

Question

go

r := mux.NewRouter().StrictSlash(true)
  //type = [order,user]
  r.HandleFunc("/api/photo/{type}/{type_id}/{file_id}", request.DownloadFile).Methods("GET")
  r.HandleFunc("/api/photo/{type}/{type_id}/{file_id}", request.DeleteFile).Methods("DELETE")
  r.HandleFunc("/api/photo/{type}", request.UploadFile).Methods("POST")

  err := http.ListenAndServe(":8080",r)

/api/photo/{type} works fine, but /api/photo/{type}/{type_id}/{file_id} gives 404. What could be the reason? The request goes to the addresses: localhost:8080/api/photo/user and /api/photo/user/123/adasd.png, respectively, only in the second case, for some reason, always 404.
serveFile returns 404 although the file exists.
"../../files/" + typeFile +"/"+ typeId + "/" + fileId this is how the path is formed. If you transfer it statically, then it works, but if you collect it, then 404.

Answer 1

/api/photo/{type}/{type_id}/{file_id}
/api/photo/123/adasd.png
And what else should be, the url does not match the mask