From f7c15071decd9a33fabece54b86e92e10009a034 Mon Sep 17 00:00:00 2001
From: Neil Alexander <neilalexander@users.noreply.github.com>
Date: Wed, 7 Oct 2020 10:30:27 +0100
Subject: [PATCH] Don't return 500s on checking to see if a remote server is
 allowed to see an event we don't know about (#1490)

---
 roomserver/internal/helpers/helpers.go | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/roomserver/internal/helpers/helpers.go b/roomserver/internal/helpers/helpers.go
index b7e6ce86..a2fbd287 100644
--- a/roomserver/internal/helpers/helpers.go
+++ b/roomserver/internal/helpers/helpers.go
@@ -2,6 +2,8 @@ package helpers
 
 import (
 	"context"
+	"database/sql"
+	"errors"
 	"fmt"
 
 	"github.com/matrix-org/dendrite/roomserver/api"
@@ -217,6 +219,9 @@ func CheckServerAllowedToSeeEvent(
 	roomState := state.NewStateResolution(db, info)
 	stateEntries, err := roomState.LoadStateAtEvent(ctx, eventID)
 	if err != nil {
+		if errors.Is(err, sql.ErrNoRows) {
+			return false, nil
+		}
 		return false, err
 	}