diff --git a/back/store.go b/back/store.go
index 3a48db7..eb4de8f 100644
--- a/back/store.go
+++ b/back/store.go
@@ -12,6 +12,8 @@ import (
 	"github.com/rickb777/date"
 )
 
+var ErrNotFound = errors.New("not found")
+
 type GenString func(length int) (string, error)
 
 type Store struct {
@@ -211,8 +213,7 @@ func (s *Store) GetEventMetadata(ctx context.Context, query GetEventMetadataQuer
 		return GetEventMetadataResult{}, err
 	}
 	if !found {
-		// TODO return a constant or a specific error type for Not Found
-		return GetEventMetadataResult{}, errors.New("not found")
+		return GetEventMetadataResult{}, ErrNotFound
 	}
 	return result, nil
 }
@@ -246,7 +247,7 @@ func (s *Store) GetEventResponseSummary(ctx context.Context, query GetEventRespo
 		return GetEventResponseSummaryResult{}, err
 	}
 	if !found {
-		return GetEventResponseSummaryResult{}, errors.New("event not found")
+		return GetEventResponseSummaryResult{}, ErrNotFound
 	}
 
 	var result GetEventResponseSummaryResult
@@ -351,8 +352,7 @@ func (s *Store) GetEventResponse(ctx context.Context, query GetEventResponseQuer
 		return GetEventResponseResult{}, err
 	}
 	if !found {
-		// TODO return a constant or typed error
-		return GetEventResponseResult{}, errors.New("not found")
+		return GetEventResponseResult{}, ErrNotFound
 	}
 
 	result.DateHours = make(map[date.Date]map[int]struct{})
diff --git a/front/server.go b/front/server.go
index f3cf45e..8116e87 100644
--- a/front/server.go
+++ b/front/server.go
@@ -119,14 +119,44 @@ func voteForm(disabled bool, st voteState) hm.Term {
 	)
 }
 
+func notFound(w http.ResponseWriter, err error, msg string) bool {
+	if err == back.ErrNotFound {
+		http.Error(w, msg, http.StatusNotFound)
+		return true
+	}
+	return false
+}
+
+func invalidForm(w http.ResponseWriter, err error) bool {
+	if err != nil {
+		http.Error(w,
+			"Invalid form values. That shouldn't have been possible. Please try again later.",
+			http.StatusBadRequest)
+		logError(err)
+		return true
+	}
+	return false
+}
+
+func logError(err error) {
+	log.Println("ERROR:", err.Error())
+}
+
+func internalServerError(w http.ResponseWriter, err error) bool {
+	if err != nil {
+		http.Error(w, "Something went wrong. Please try again later.", http.StatusInternalServerError)
+		logError(err)
+		return true
+	}
+	return false
+}
+
 func (h *handler) handleVote(w http.ResponseWriter, r *http.Request) {
 	eventAlphaID := r.URL.Query().Get(fieldNameEventID)
 	event, err := h.store.GetEventMetadata(context.Background(), back.GetEventMetadataQuery{
 		AlphaID: eventAlphaID,
 	})
-	// TODO return 404 if event not found
-	if err != nil {
-		fmt.Fprint(w, err)
+	if notFound(w, err, "Event not found") || internalServerError(w, err) {
 		return
 	}
 
@@ -144,9 +174,7 @@ func (h *handler) handleVote(w http.ResponseWriter, r *http.Request) {
 
 func (h *handler) handleDoVote(w http.ResponseWriter, r *http.Request) {
 	err := r.ParseForm()
-	if err != nil {
-		log.Println(err)
-		http.Error(w, "invalid form values", http.StatusBadRequest)
+	if invalidForm(w, err) {
 		return
 	}
 
@@ -161,28 +189,20 @@ func (h *handler) handleDoVote(w http.ResponseWriter, r *http.Request) {
 		var dateString string
 		var hour int
 		_, err := fmt.Sscanf(dateHourString, "%8s-%02d", &dateString, &hour)
-		if err != nil {
-			log.Println(err)
-			http.Error(w, "invalid form values", http.StatusBadRequest)
+		if invalidForm(w, err) {
 			return
 		}
 		d, err := date.Parse("20060102", dateString)
-		if err != nil {
-			log.Println(err)
-			http.Error(w, "invalid form values", http.StatusBadRequest)
+		if invalidForm(w, err) {
 			return
 		}
-		fmt.Println("parsed date/hour:", d, hour)
 		if cmd.DateHours[d] == nil {
 			cmd.DateHours[d] = make(map[int]struct{})
 		}
 		cmd.DateHours[d][hour] = struct{}{}
 	}
 	eventResponse, err := h.store.CreateEventResponse(r.Context(), cmd)
-	if err != nil {
-		log.Println(err)
-		// TODO handle not found
-		http.Error(w, "internal server error", http.StatusInternalServerError)
+	if notFound(w, err, "Event not found") || internalServerError(w, err) {
 		return
 	}
 
@@ -197,20 +217,14 @@ func (h *handler) handleVoteSuccess(w http.ResponseWriter, r *http.Request) {
 		EventAlphaID:    r.URL.Query().Get(fieldNameEventID),
 		ResponseAlphaID: r.URL.Query().Get(fieldNameResponseID),
 	})
-	if err != nil {
-		log.Println(err)
-		// TODO handle not found
-		http.Error(w, "internal server error", http.StatusInternalServerError)
+	if notFound(w, err, "Event response not found.") || internalServerError(w, err) {
 		return
 	}
 
 	event, err := h.store.GetEventMetadata(r.Context(), back.GetEventMetadataQuery{
 		AlphaID: r.URL.Query().Get(fieldNameEventID),
 	})
-	if err != nil {
-		log.Println(err)
-		// TODO handle not found
-		http.Error(w, "internal server error", http.StatusInternalServerError)
+	if notFound(w, err, "Event not found") || internalServerError(w, err) {
 		return
 	}
 
@@ -256,18 +270,16 @@ func (h *handler) handleCreate(w http.ResponseWriter, r *http.Request) {
 func (h *handler) handleDoCreate(w http.ResponseWriter, r *http.Request) {
 	// TODO consider redirecting to admin
 	earliest, err := date.Parse(formDateLayout, r.FormValue(fieldNameEarliest))
-	if err != nil {
-		fmt.Fprint(w, "bad earliest date")
+	if invalidForm(w, err) {
 		return
 	}
 	latest, err := date.Parse(formDateLayout, r.FormValue(fieldNameLatest))
-	if err != nil {
-		fmt.Fprint(w, "bad latest date")
+	if invalidForm(w, err) {
 		return
 	}
 	eventName := r.FormValue(fieldNameEventName)
 	if eventName == "" {
-		fmt.Fprint(w, "event name is required")
+		fmt.Fprint(w, "Event name is required")
 		return
 	}
 	description := r.FormValue(fieldNameDescription)
@@ -294,10 +306,7 @@ func (h *handler) handleCreateSuccess(w http.ResponseWriter, r *http.Request) {
 	event, err := h.store.GetEventMetadata(r.Context(), back.GetEventMetadataQuery{
 		AlphaID: eventID,
 	})
-	if err != nil {
-		log.Println(err)
-		// TODO handle not found
-		http.Error(w, "internal server error", http.StatusInternalServerError)
+	if notFound(w, err, "Event not found") || internalServerError(w, err) {
 		return
 	}
 
@@ -346,9 +355,7 @@ func (h *handler) handleAdmin(w http.ResponseWriter, r *http.Request) {
 	metadata, err := h.store.GetEventMetadata(context.Background(), back.GetEventMetadataQuery{
 		AlphaID: eventID,
 	})
-	// TODO return 404 if event not found
-	if err != nil {
-		fmt.Fprint(w, err)
+	if notFound(w, err, "Event not found") || internalServerError(w, err) {
 		return
 	}