2020-03-31 12:30:15,350 - synapse.rest.media.v1.preview_url_resource - 401 - INFO - expire_url_cache_data-1 - Running url preview cache expiry
2020-03-31 12:30:15,351 - synapse.metrics.background_process_metrics - 215 - ERROR - expire_url_cache_data-1 - Background process 'expire_url_cache_data' threw an exception
Traceback (most recent call last):
  File "/home/rav/work/synapse/env3/lib/python3.6/site-packages/twisted/internet/defer.py", line 1418, in _inlineCallbacks
    result = g.send(result)
StopIteration: []

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/rav/work/synapse/env3/lib/python3.6/site-packages/twisted/internet/defer.py", line 1418, in _inlineCallbacks
    result = g.send(result)
StopIteration: []

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/rav/work/synapse/synapse/metrics/background_process_metrics.py", line 213, in run
    return (yield result)
  File "/home/rav/work/synapse/env3/lib/python3.6/site-packages/twisted/internet/defer.py", line 1418, in _inlineCallbacks
    result = g.send(result)
  File "/home/rav/work/synapse/synapse/rest/media/v1/preview_url_resource.py", line 430, in _expire_url_cache_data
    await self.store.delete_url_cache(removed_media)
TypeError: object NoneType can't be used in 'await' expression