diff --git a/Duplicati/Library/Backend/S3/S3Backend.cs b/Duplicati/Library/Backend/S3/S3Backend.cs
index 262a8433d..849e8b5da 100644
--- a/Duplicati/Library/Backend/S3/S3Backend.cs
+++ b/Duplicati/Library/Backend/S3/S3Backend.cs
@@ -247,6 +247,10 @@ namespace Duplicati.Library.Backend
             if (!options.ContainsKey("s3-ext-forcepathstyle") && !hostname.EndsWith(".amazonaws.com", StringComparison.OrdinalIgnoreCase))
                 options["s3-ext-forcepathstyle"] = "true";
 
+            // Validate that hostname doesn't contain a path
+            if (hostname.Contains('/') || hostname.Contains('\\'))
+                throw new UserInformationException(Strings.S3Backend.NoPathAllowedInEndpointError, "S3NoPathInEndpoint");
+
 
             var s3ClientOptionValue = options.GetValueOrDefault(S3_CLIENT_OPTION);
 
diff --git a/Duplicati/Library/Backend/S3/Strings.cs b/Duplicati/Library/Backend/S3/Strings.cs
index fc77f6ec6..61627d335 100644
--- a/Duplicati/Library/Backend/S3/Strings.cs
+++ b/Duplicati/Library/Backend/S3/Strings.cs
@@ -58,6 +58,7 @@ namespace Duplicati.Library.Backend.Strings
         public static string DescriptionRecursiveListShort { get { return LC.L(@"Use this option to list all files in the bucket"); } }
         public static string DescriptionRecursiveListLong { get { return LC.L(@"To reduce the number of objects listed, the default is to only list the first level of objects. Use this option to list all objects in the bucket."); } }
         public static string UnknownS3ClientError(string client) { return LC.L(@"Unknown S3 client: {0}", client); }
+        public static string NoPathAllowedInEndpointError { get { return LC.L(@"No path allowed in endpoint"); } }
     }
 
     internal static class S3Config