diff --git a/dotnet/src/dotnetframework/GxClasses/Helpers/GXRestUtils.cs b/dotnet/src/dotnetframework/GxClasses/Helpers/GXRestUtils.cs
index b8ffa60af..f2198a30d 100644
--- a/dotnet/src/dotnetframework/GxClasses/Helpers/GXRestUtils.cs
+++ b/dotnet/src/dotnetframework/GxClasses/Helpers/GXRestUtils.cs
@@ -31,7 +31,7 @@ internal static bool IsUploadURL(HttpContext httpContext)
 		}
 		internal static void CacheUploadFile(string fileGuid, string realFileName, string realFileExtension, GxFile temporalFile, IGxContext gxContext)
 		{
-			CacheAPI.FilesCache.Set(fileGuid, JSONHelper.Serialize(new UploadCachedFile() { path = temporalFile.GetAbsoluteName(), fileExtension = realFileExtension, fileName = realFileName }), GxRestPrefix.UPLOAD_TIMEOUT);
+			CacheAPI.FilesCache.Set(fileGuid, JSONHelper.Serialize(new UploadCachedFile() { path = temporalFile.GetURI(), fileExtension = realFileExtension, fileName = realFileName }), GxRestPrefix.UPLOAD_TIMEOUT);
 			GXFileWatcher.Instance.AddTemporaryFile(temporalFile, gxContext);
 		}
 		internal static string GetUploadFileGuid()
diff --git a/dotnet/src/dotnetframework/Providers/Storage/GXAmazonS3/ExternalProviderS3.cs b/dotnet/src/dotnetframework/Providers/Storage/GXAmazonS3/ExternalProviderS3.cs
index c7a26cd14..7a7aad213 100644
--- a/dotnet/src/dotnetframework/Providers/Storage/GXAmazonS3/ExternalProviderS3.cs
+++ b/dotnet/src/dotnetframework/Providers/Storage/GXAmazonS3/ExternalProviderS3.cs
@@ -357,11 +357,13 @@ private S3CannedACL GetCannedACL(GxFileType acl)
 
 		public string Upload(string fileName, Stream stream, GxFileType destFileType)
 		{
+			MemoryStream ms = new MemoryStream();
+			stream.CopyTo(ms);//can determine PutObjectRequest.Headers.ContentLength. Avoid error Could not determine content length
 			PutObjectRequest objectRequest = new PutObjectRequest()
 			{
 				BucketName = Bucket,
 				Key = fileName,
-				InputStream = stream,
+				InputStream = ms,
 				CannedACL = GetCannedACL(destFileType)
 			};
 			if (TryGetContentType(fileName, out string mimeType)) {