2 files changed, 18 insertions, 10 deletions

diff --git a/Emby.Server.Implementations/HttpServer/HttpListenerHost.cs b/Emby.Server.Implementations/HttpServer/HttpListenerHost.cs
index 72667a314..5ae65a4e3 100644
--- a/Emby.Server.Implementations/HttpServer/HttpListenerHost.cs
+++ b/Emby.Server.Implementations/HttpServer/HttpListenerHost.cs
@@ -239,7 +239,7 @@ namespace Emby.Server.Implementations.HttpServer
             }
         }
 
-        private async Task ErrorHandler(Exception ex, IRequest httpReq, bool logExceptionStackTrace)
+        private async Task ErrorHandler(Exception ex, IRequest httpReq, bool logExceptionStackTrace, string urlToLog)
         {
             try
             {
@@ -247,11 +247,11 @@ namespace Emby.Server.Implementations.HttpServer
 
                 if (logExceptionStackTrace)
                 {
-                    _logger.LogError(ex, "Error processing request");
+                    _logger.LogError(ex, "Error processing request. URL: {Url}", urlToLog);
                 }
                 else
                 {
-                    _logger.LogError("Error processing request: {Message}", ex.Message);
+                    _logger.LogError("Error processing request: {Message}. URL: {Url}", ex.Message.TrimEnd('.'), urlToLog);
                 }
 
                 var httpRes = httpReq.Response;
@@ -271,7 +271,7 @@ namespace Emby.Server.Implementations.HttpServer
             }
             catch (Exception errorEx)
             {
-                _logger.LogError(errorEx, "Error this.ProcessRequest(context)(Exception while writing error to the response)");
+                _logger.LogError(errorEx, "Error this.ProcessRequest(context)(Exception while writing error to the response). URL: {Url}", urlToLog);
             }
         }
 
@@ -456,7 +456,7 @@ namespace Emby.Server.Implementations.HttpServer
             var stopWatch = new Stopwatch();
             stopWatch.Start();
             var httpRes = httpReq.Response;
-            string urlToLog = null;
+            string urlToLog = GetUrlToLog(urlString);
             string remoteIp = httpReq.RemoteIp;
 
             try
@@ -502,8 +502,6 @@ namespace Emby.Server.Implementations.HttpServer
                     return;
                 }
 
-                urlToLog = GetUrlToLog(urlString);
-
                 if (string.Equals(localPath, _baseUrlPrefix + "/", StringComparison.OrdinalIgnoreCase)
                     || string.Equals(localPath, _baseUrlPrefix, StringComparison.OrdinalIgnoreCase)
                     || string.Equals(localPath, "/", StringComparison.OrdinalIgnoreCase)
@@ -553,7 +551,7 @@ namespace Emby.Server.Implementations.HttpServer
                     || ex is OperationCanceledException
                     || ex is SecurityException
                     || ex is FileNotFoundException;
-                await ErrorHandler(ex, httpReq, ignoreStackTrace).ConfigureAwait(false);
+                await ErrorHandler(ex, httpReq, !ignoreStackTrace, urlToLog).ConfigureAwait(false);
             }
             finally
             {
diff --git a/Emby.Server.Implementations/HttpServer/HttpResultFactory.cs b/Emby.Server.Implementations/HttpServer/HttpResultFactory.cs
index b42662420..464ca3a0b 100644
--- a/Emby.Server.Implementations/HttpServer/HttpResultFactory.cs
+++ b/Emby.Server.Implementations/HttpServer/HttpResultFactory.cs
@@ -28,6 +28,12 @@ namespace Emby.Server.Implementations.HttpServer
     /// </summary>
     public class HttpResultFactory : IHttpResultFactory
     {
+        // Last-Modified and If-Modified-Since must follow strict date format,
+        // see https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/If-Modified-Since
+        private const string HttpDateFormat = "ddd, dd MMM yyyy HH:mm:ss \"GMT\"";
+        // We specifically use en-US culture because both day of week and month names require it
+        private static readonly CultureInfo _enUSculture = new CultureInfo("en-US", false);
+
         /// <summary>
         /// The logger.
         /// </summary>
@@ -420,7 +426,11 @@ namespace Emby.Server.Implementations.HttpServer
 
             if (!noCache)
             {
-                DateTime.TryParse(requestContext.Headers[HeaderNames.IfModifiedSince], out var ifModifiedSinceHeader);
+                if (!DateTime.TryParseExact(requestContext.Headers[HeaderNames.IfModifiedSince], HttpDateFormat, _enUSculture, DateTimeStyles.AssumeUniversal, out var ifModifiedSinceHeader))
+                {
+                    _logger.LogDebug("Failed to parse If-Modified-Since header date: {0}", requestContext.Headers[HeaderNames.IfModifiedSince]);
+                    return null;
+                }
 
                 if (IsNotModified(ifModifiedSinceHeader, options.CacheDuration, options.DateLastModified))
                 {
@@ -629,7 +639,7 @@ namespace Emby.Server.Implementations.HttpServer
 
             if (lastModifiedDate.HasValue)
             {
-                responseHeaders[HeaderNames.LastModified] = lastModifiedDate.Value.ToString(CultureInfo.InvariantCulture);
+                responseHeaders[HeaderNames.LastModified] = lastModifiedDate.Value.ToUniversalTime().ToString(HttpDateFormat, _enUSculture);
             }
         }