Datastore max size is 1,000,000, not 1M(=2^20).

app.yaml

@@ -1,5 +1,5 @@
 application: fanfictionloader
-version: 2-6-beta
+version: 3-0-alpha
 runtime: python
 api_version: 1
 

main.py

@@ -345,9 +345,9 @@ class FanfictionDownloaderTask(webapp.RequestHandler):
 			while( len(data) > 0 ):
 				DownloadData(download=download,
 					     index=index,
-					     blob=data[:1024*1000]).put()
+					     blob=data[:1000000]).put()
 				index += 1
-				data = data[1024*1000:]
+				data = data[1000000:]
 			download.completed=True
 			download.put()
 			

queue.yaml

@@ -4,4 +4,4 @@ queue:
 - name: download
   rate: 10/s
   retry_parameters:
-    task_retry_limit: 3
+    task_retry_limit: 2