diff --git a/cmd/owl/web/auth_handler.go b/cmd/owl/web/auth_handler.go
index 1c15a2c..1dabdea 100644
--- a/cmd/owl/web/auth_handler.go
+++ b/cmd/owl/web/auth_handler.go
@@ -79,33 +79,53 @@ func userAuthHandler(repo *owl.Repository) func(http.ResponseWriter, *http.Reque
 		}
 		if len(missing_params) > 0 {
 			w.WriteHeader(http.StatusBadRequest)
-			w.Write([]byte(fmt.Sprintf("Missing parameters: %s", strings.Join(missing_params, ", "))))
+			html, _ := owl.RenderUserError(user, owl.ErrorMessage{
+				Error:   "Missing parameters",
+				Message: "Missing parameters: " + strings.Join(missing_params, ", "),
+			})
+			w.Write([]byte(html))
 			return
 		}
-		if responseType != "id" {
+		if responseType == "id" {
 			responseType = "code"
 		}
 		if responseType != "code" {
 			w.WriteHeader(http.StatusBadRequest)
-			w.Write([]byte("Invalid response_type. Must be 'code' ('id' converted to 'code' for legacy support)."))
+			html, _ := owl.RenderUserError(user, owl.ErrorMessage{
+				Error:   "Invalid response_type",
+				Message: "Must be 'code' ('id' converted to 'code' for legacy support).",
+			})
+			w.Write([]byte(html))
 			return
 		}
 		if codeChallengeMethod != "" && (codeChallengeMethod != "S256" && codeChallengeMethod != "plain") {
 			w.WriteHeader(http.StatusBadRequest)
-			w.Write([]byte("Invalid code_challenge_method. Must be 'S256' or 'plain'."))
+			html, _ := owl.RenderUserError(user, owl.ErrorMessage{
+				Error:   "Invalid code_challenge_method",
+				Message: "Must be 'S256' or 'plain'.",
+			})
+			w.Write([]byte(html))
 			return
 		}
 
 		client_id_url, err := url.Parse(clientId)
 		if err != nil {
 			w.WriteHeader(http.StatusBadRequest)
-			w.Write([]byte("Invalid client_id."))
+			html, _ := owl.RenderUserError(user, owl.ErrorMessage{
+				Error:   "Invalid client_id",
+				Message: "Invalid client_id: " + clientId,
+			})
+			w.Write([]byte(html))
 			return
 		}
 		redirect_uri_url, err := url.Parse(redirectUri)
 		if err != nil {
 			w.WriteHeader(http.StatusBadRequest)
-			w.Write([]byte("Invalid redirect_uri."))
+			html, _ := owl.RenderUserError(user, owl.ErrorMessage{
+				Error:   "Invalid redirect_uri",
+				Message: "Invalid redirect_uri: " + redirectUri,
+			})
+			w.Write([]byte(html))
 			return
 		}
 		if client_id_url.Host != redirect_uri_url.Host || client_id_url.Scheme != redirect_uri_url.Scheme {
@@ -122,7 +142,11 @@ func userAuthHandler(repo *owl.Repository) func(http.ResponseWriter, *http.Reque
 			}
 			if !is_registered {
 				w.WriteHeader(http.StatusBadRequest)
-				w.Write([]byte("Invalid redirect_uri. Must be registered with client_id."))
+				html, _ := owl.RenderUserError(user, owl.ErrorMessage{
+					Error:   "Invalid redirect_uri",
+					Message: redirectUri + " is not registered for " + clientId,
+				})
+				w.Write([]byte(html))
 				return
 			}
 		}
@@ -155,10 +179,13 @@ func userAuthHandler(repo *owl.Repository) func(http.ResponseWriter, *http.Reque
 		if err != nil {
 			println("Error rendering auth page: ", err.Error())
 			w.WriteHeader(http.StatusInternalServerError)
-			w.Write([]byte("Internal server error"))
+			html, _ := owl.RenderUserError(user, owl.ErrorMessage{
+				Error:   "Internal Server Error",
+				Message: "Internal Server Error",
+			})
+			w.Write([]byte(html))
 			return
 		}
-		println("Rendering auth page for user", user.Name())
 		w.Write([]byte(html))
 	}
 }
@@ -292,7 +319,11 @@ func userAuthVerifyHandler(repo *owl.Repository) func(http.ResponseWriter, *http
 		if err != nil {
 			println("Error parsing form: ", err.Error())
 			w.WriteHeader(http.StatusBadRequest)
-			w.Write([]byte("Error parsing form"))
+			html, _ := owl.RenderUserError(user, owl.ErrorMessage{
+				Error:   "Error parsing form",
+				Message: "Error parsing form",
+			})
+			w.Write([]byte(html))
 			return
 		}
 		password := r.FormValue("password")
@@ -311,13 +342,21 @@ func userAuthVerifyHandler(repo *owl.Repository) func(http.ResponseWriter, *http
 		if err != nil {
 			println("Error getting csrf token from cookie: ", err.Error())
 			w.WriteHeader(http.StatusBadRequest)
-			w.Write([]byte("Error getting csrf token from cookie"))
+			html, _ := owl.RenderUserError(user, owl.ErrorMessage{
+				Error:   "CSRF Error",
+				Message: "Error getting csrf token from cookie",
+			})
+			w.Write([]byte(html))
 			return
 		}
 		if formCsrfToken != cookieCsrfToken.Value {
 			println("Invalid csrf token")
 			w.WriteHeader(http.StatusBadRequest)
-			w.Write([]byte("Invalid csrf token"))
+			html, _ := owl.RenderUserError(user, owl.ErrorMessage{
+				Error:   "CSRF Error",
+				Message: "Invalid csrf token",
+			})
+			w.Write([]byte(html))
 			return
 		}
 
@@ -342,7 +381,11 @@ func userAuthVerifyHandler(repo *owl.Repository) func(http.ResponseWriter, *http
 			if err != nil {
 				println("Error generating code: ", err.Error())
 				w.WriteHeader(http.StatusInternalServerError)
-				w.Write([]byte("Internal server error"))
+				html, _ := owl.RenderUserError(user, owl.ErrorMessage{
+					Error:   "Internal Server Error",
+					Message: "Error generating code",
+				})
+				w.Write([]byte(html))
 				return
 			}
 			http.Redirect(w, r,
diff --git a/cmd/owl/web/handler.go b/cmd/owl/web/handler.go
index c835c4c..4c5a160 100644
--- a/cmd/owl/web/handler.go
+++ b/cmd/owl/web/handler.go
@@ -51,7 +51,11 @@ func userIndexHandler(repo *owl.Repository) func(http.ResponseWriter, *http.Requ
 		if err != nil {
 			println("Error rendering index page: ", err.Error())
 			w.WriteHeader(http.StatusInternalServerError)
-			w.Write([]byte("Internal server error"))
+			html, _ := owl.RenderUserError(user, owl.ErrorMessage{
+				Error:   "Internal server error",
+				Message: "Internal server error",
+			})
+			w.Write([]byte(html))
 			return
 		}
 		println("Rendering index page for user", user.Name())
@@ -163,7 +167,11 @@ func userRSSHandler(repo *owl.Repository) func(http.ResponseWriter, *http.Reques
 		if err != nil {
 			println("Error rendering index page: ", err.Error())
 			w.WriteHeader(http.StatusInternalServerError)
-			w.Write([]byte("Internal server error"))
+			html, _ := owl.RenderUserError(user, owl.ErrorMessage{
+				Error:   "Internal server error",
+				Message: "Internal server error",
+			})
+			w.Write([]byte(html))
 			return
 		}
 		println("Rendering index page for user", user.Name())
@@ -186,14 +194,14 @@ func postHandler(repo *owl.Repository) func(http.ResponseWriter, *http.Request,
 
 		if err != nil {
 			println("Error getting post: ", err.Error())
-			notFoundHandler(repo)(w, r)
+			notFoundUserHandler(repo, user)(w, r)
 			return
 		}
 
 		meta := post.Meta()
 		if meta.Draft {
 			println("Post is a draft")
-			notFoundHandler(repo)(w, r)
+			notFoundUserHandler(repo, user)(w, r)
 			return
 		}
 
@@ -201,7 +209,11 @@ func postHandler(repo *owl.Repository) func(http.ResponseWriter, *http.Request,
 		if err != nil {
 			println("Error rendering post: ", err.Error())
 			w.WriteHeader(http.StatusInternalServerError)
-			w.Write([]byte("Internal server error"))
+			html, _ := owl.RenderUserError(user, owl.ErrorMessage{
+				Error:   "Internal server error",
+				Message: "Internal server error",
+			})
+			w.Write([]byte(html))
 			return
 		}
 		println("Rendering post", postId)
@@ -224,13 +236,13 @@ func postMediaHandler(repo *owl.Repository) func(http.ResponseWriter, *http.Requ
 		post, err := user.GetPost(postId)
 		if err != nil {
 			println("Error getting post: ", err.Error())
-			notFoundHandler(repo)(w, r)
+			notFoundUserHandler(repo, user)(w, r)
 			return
 		}
 		filepath = path.Join(post.MediaDir(), filepath)
 		if _, err := os.Stat(filepath); err != nil {
 			println("Error getting file: ", err.Error())
-			notFoundHandler(repo)(w, r)
+			notFoundUserHandler(repo, user)(w, r)
 			return
 		}
 		http.ServeFile(w, r, filepath)
@@ -250,7 +262,7 @@ func userMediaHandler(repo *owl.Repository) func(http.ResponseWriter, *http.Requ
 		filepath = path.Join(user.MediaDir(), filepath)
 		if _, err := os.Stat(filepath); err != nil {
 			println("Error getting file: ", err.Error())
-			notFoundHandler(repo)(w, r)
+			notFoundUserHandler(repo, user)(w, r)
 			return
 		}
 		http.ServeFile(w, r, filepath)
@@ -269,3 +281,20 @@ func notFoundHandler(repo *owl.Repository) func(http.ResponseWriter, *http.Reque
 		w.Write([]byte("Not found"))
 	}
 }
+
+func notFoundUserHandler(repo *owl.Repository, user owl.User) func(http.ResponseWriter, *http.Request) {
+	return func(w http.ResponseWriter, r *http.Request) {
+		path := r.URL.Path
+		aliases, _ := repo.PostAliases()
+		if _, ok := aliases[path]; ok {
+			http.Redirect(w, r, aliases[path].UrlPath(), http.StatusMovedPermanently)
+			return
+		}
+		w.WriteHeader(http.StatusNotFound)
+		html, _ := owl.RenderUserError(user, owl.ErrorMessage{
+			Error:   "Not found",
+			Message: "The page you requested could not be found",
+		})
+		w.Write([]byte(html))
+	}
+}
diff --git a/embed/error.html b/embed/error.html
new file mode 100644
index 0000000..e3000ab
--- /dev/null
+++ b/embed/error.html
@@ -0,0 +1,4 @@
+<article style="background-color: #dd867f;color: #481212;">
+    <h3>{{ .Error }}</h3>
+    {{ .Message }}
+</article>
\ No newline at end of file
diff --git a/renderer.go b/renderer.go
index 3ef6df9..1ef0ad2 100644
--- a/renderer.go
+++ b/renderer.go
@@ -35,6 +35,11 @@ type AuthRequestData struct {
 	CsrfToken           string
 }
 
+type ErrorMessage struct {
+	Error   string
+	Message string
+}
+
 func renderEmbedTemplate(templateFile string, data interface{}) (string, error) {
 	templateStr, err := embed_files.ReadFile(templateFile)
 	if err != nil {
@@ -80,9 +85,8 @@ func renderIntoBaseTemplate(user User, data PageContent) (string, error) {
 	}
 
 	var html bytes.Buffer
-	t.Execute(&html, full_data)
-
-	return html.String(), nil
+	err = t.Execute(&html, full_data)
+	return html.String(), err
 }
 
 func renderPostContent(post *Post) (string, error) {
@@ -137,6 +141,18 @@ func RenderUserAuthPage(reqData AuthRequestData) (string, error) {
 	})
 }
 
+func RenderUserError(user User, error ErrorMessage) (string, error) {
+	errHtml, err := renderEmbedTemplate("embed/error.html", error)
+	if err != nil {
+		return "", err
+	}
+
+	return renderIntoBaseTemplate(user, PageContent{
+		Title:   "Error",
+		Content: template.HTML(errHtml),
+	})
+}
+
 func RenderUserList(repo Repository) (string, error) {
 	baseTemplate, _ := repo.Template()
 	users, _ := repo.Users()