Update view_utils.py:

It looks like the previous check that determined if the file_version was None is broken in python3:
https://stackoverflow.com/questions/8961005/comparing-none-with-built-in-types-using-arithmetic-operators
So the comparison of log.file_version=None >=0 would error out. I added the conditional to the top of the block and combined a couple of lines.

gracedb/events/view_utils.py

@@ -375,10 +375,8 @@ def eventLogToDict(log, request=None):
     taglist_uri = api_reverse("events:eventlogtag-list",
             args=[log.event.graceid, log.N],
             request=request)
-    if log.filename:
-        actual_filename = log.filename
-        if log.file_version >= 0:
-            actual_filename += ',%d' % log.file_version
+    if log.filename and log.file_version is not None:
+        actual_filename = log.filename + ',%d' % log.file_version
         # NOTE: the reverse function will return a urlquoted
         # result, so we don't need urlquote here. Effectively
         # escaping twice results in wrong urls.