diff --git a/internal/net/gphttp/error.go b/internal/net/gphttp/error.go
index 47a1acad..8300a5ba 100644
--- a/internal/net/gphttp/error.go
+++ b/internal/net/gphttp/error.go
@@ -2,13 +2,10 @@ package gphttp
 
 import (
 	"context"
-	"encoding/json"
 	"errors"
-	"fmt"
 	"net/http"
 	"syscall"
 
-	"github.com/yusing/godoxy/internal/gperr"
 	"github.com/yusing/godoxy/internal/net/gphttp/httpheaders"
 )
 
@@ -33,76 +30,3 @@ func ServerError(w http.ResponseWriter, r *http.Request, err error, code ...int)
 	}
 	http.Error(w, http.StatusText(code[0]), code[0])
 }
-
-// ClientError is for responding to client errors.
-//
-// It returns http.StatusBadRequest with reason to the client.
-// Status code can be specified as an argument.
-//
-// For JSON marshallable errors (e.g. gperr.Error), it returns the error details as JSON.
-// Otherwise, it returns the error details as plain text.
-func ClientError(w http.ResponseWriter, r *http.Request, err error, code ...int) {
-	if len(code) == 0 {
-		code = []int{http.StatusBadRequest}
-	}
-	w.WriteHeader(code[0])
-	accept := GetAccept(r.Header)
-	switch {
-	case accept.AcceptJSON():
-		w.Header().Set("Content-Type", "application/json")
-		json.NewEncoder(w).Encode(err)
-	case accept.AcceptMarkdown():
-		w.Header().Set("Content-Type", "text/markdown")
-		w.Write(gperr.Markdown(err))
-	default:
-		w.Header().Set("Content-Type", "text/plain")
-		w.Write(gperr.Plain(err))
-	}
-}
-
-// JSONError returns a JSON response of gperr.Error with the given status code.
-func JSONError(w http.ResponseWriter, err gperr.Error, code int) {
-	w.Header().Set("Content-Type", "application/json")
-	w.WriteHeader(code)
-	json.NewEncoder(w).Encode(err)
-}
-
-// BadRequest returns a Bad Request response with the given error message.
-func BadRequest(w http.ResponseWriter, err string, code ...int) {
-	if len(code) == 0 {
-		code = []int{http.StatusBadRequest}
-	}
-	w.WriteHeader(code[0])
-	w.Write([]byte(err))
-}
-
-// Unauthorized returns an Unauthorized response with the given error message.
-func Unauthorized(w http.ResponseWriter, err string) {
-	BadRequest(w, err, http.StatusUnauthorized)
-}
-
-// Forbidden returns a Forbidden response with the given error message.
-func Forbidden(w http.ResponseWriter, err string) {
-	BadRequest(w, err, http.StatusForbidden)
-}
-
-// NotFound returns a Not Found response with the given error message.
-func NotFound(w http.ResponseWriter, err string) {
-	BadRequest(w, err, http.StatusNotFound)
-}
-
-func MissingKey(w http.ResponseWriter, k string) {
-	BadRequest(w, k+" is required", http.StatusBadRequest)
-}
-
-func InvalidKey(w http.ResponseWriter, k string) {
-	BadRequest(w, k+" is invalid", http.StatusBadRequest)
-}
-
-func KeyAlreadyExists(w http.ResponseWriter, k, v string) {
-	BadRequest(w, fmt.Sprintf("%s %q already exists", k, v), http.StatusBadRequest)
-}
-
-func ValueNotFound(w http.ResponseWriter, k, v string) {
-	BadRequest(w, fmt.Sprintf("%s %q not found", k, v), http.StatusNotFound)
-}
diff --git a/internal/net/gphttp/middleware/captcha/middleware.go b/internal/net/gphttp/middleware/captcha/middleware.go
index baa58892..604e21c8 100644
--- a/internal/net/gphttp/middleware/captcha/middleware.go
+++ b/internal/net/gphttp/middleware/captcha/middleware.go
@@ -32,7 +32,7 @@ func PreRequest(p Provider, w http.ResponseWriter, r *http.Request) (proceed boo
 	}
 
 	if !gphttp.GetAccept(r.Header).AcceptHTML() {
-		gphttp.Forbidden(w, "Captcha is required")
+		http.Error(w, "Captcha is required", http.StatusForbidden)
 		return false
 	}
 
@@ -45,7 +45,9 @@ func PreRequest(p Provider, w http.ResponseWriter, r *http.Request) (proceed boo
 			http.Redirect(w, r, r.URL.Path, http.StatusFound)
 			return false
 		}
-		gphttp.Unauthorized(w, err.Error())
+
+		log.Warn().Err(err).Str("url", r.URL.String()).Str("remote_addr", r.RemoteAddr).Msg("failed to verify captcha")
+		http.Error(w, "Failed to verify captcha", http.StatusUnauthorized)
 		return false
 	}