500 errors with "duplicate key value" on local_media_repository_thumbn_media_id_thumbnail_width_thum_key

[532910]

dynamic_thumbnails are enabled
matrix-synapse 1.15.1-1~bpo10
debian buster

% curl 'https://matrix.outerface.net/_matrix/media/r0/thumbnail/outerface.net/pwJGenkxEQAsZUFtmdCjriRH?width=32&height=32'
{
    "errcode": "M_UNKNOWN",
    "error": "Internal server error"
}

2020-07-21 23:03:07,667 - synapse.http.server - 113 - ERROR - GET-160797- Failed handle request via 'ThumbnailResource': <XForwardedForRequest at 0x7f2d0c83f8d0 method='GET' uri='/_matrix/media/r0/thumbnail/outerface.net/pwJGenkxEQAsZUFtmdCjriRH?width=32&height=32' clientproto='HTTP/1.0' site=8008>
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/synapse/http/server.py", line 81, in wrapped_request_handler
    await h(self, request)
  File "/usr/lib/python3/dist-packages/synapse/rest/media/v1/thumbnail_resource.py", line 62, in _async_render_GET
    request, media_id, width, height, method, m_type
  File "/usr/lib/python3/dist-packages/synapse/rest/media/v1/thumbnail_resource.py", line 175, in _select_or_generate_local_thumbnail
    url_cache=media_info["url_cache"],
  File "/usr/lib/python3/dist-packages/synapse/rest/media/v1/media_repository.py", line 495, in generate_local_exact_thumbnail
    media_id, t_width, t_height, t_type, t_method, t_len
  File "/usr/lib/python3/dist-packages/twisted/internet/defer.py", line 1416, in _inlineCallbacks
    result = result.throwExceptionIntoGenerator(g)
  File "/usr/lib/python3/dist-packages/twisted/python/failure.py", line 491, in throwExceptionIntoGenerator
    return g.throw(self.type, self.value, self.tb)
  File "/usr/lib/python3/dist-packages/synapse/storage/database.py", line 634, in simple_insert
    yield self.runInteraction(desc, self.simple_insert_txn, table, values)
  File "/usr/lib/python3/dist-packages/twisted/internet/defer.py", line 1416, in _inlineCallbacks
    result = result.throwExceptionIntoGenerator(g)
  File "/usr/lib/python3/dist-packages/twisted/python/failure.py", line 491, in throwExceptionIntoGenerator
    return g.throw(self.type, self.value, self.tb)
  File "/usr/lib/python3/dist-packages/synapse/storage/database.py", line 527, in runInteraction
    **kwargs
  File "/usr/lib/python3/dist-packages/twisted/internet/defer.py", line 1416, in _inlineCallbacks
    result = result.throwExceptionIntoGenerator(g)
  File "/usr/lib/python3/dist-packages/twisted/python/failure.py", line 491, in throwExceptionIntoGenerator
    return g.throw(self.type, self.value, self.tb)
  File "/usr/lib/python3/dist-packages/synapse/storage/database.py", line 575, in runWithConnection
    self._db_pool.runWithConnection(inner_func, *args, **kwargs)
  File "/usr/lib/python3/dist-packages/twisted/python/threadpool.py", line 250, in inContext
    result = inContext.theWork()
  File "/usr/lib/python3/dist-packages/twisted/python/threadpool.py", line 266, in <lambda>
    inContext.theWork = lambda: context.call(ctx, func, *args, **kw)
  File "/usr/lib/python3/dist-packages/twisted/python/context.py", line 122, in callWithContext
    return self.currentContext().callWithContext(ctx, func, *args, **kw)
  File "/usr/lib/python3/dist-packages/twisted/python/context.py", line 85, in callWithContext
    return func(*args,**kw)
  File "/usr/lib/python3/dist-packages/twisted/enterprise/adbapi.py", line 306, in _runWithConnection
    compat.reraise(excValue, excTraceback)
  File "/usr/lib/python3/dist-packages/twisted/python/compat.py", line 464, in reraise
    raise exception.with_traceback(traceback)
  File "/usr/lib/python3/dist-packages/twisted/enterprise/adbapi.py", line 297, in _runWithConnection
    result = func(conn, *args, **kw)
  File "/usr/lib/python3/dist-packages/synapse/storage/database.py", line 572, in inner_func
    return func(conn, *args, **kwargs)
  File "/usr/lib/python3/dist-packages/synapse/storage/database.py", line 418, in new_transaction
    r = func(cursor, *args, **kwargs)
  File "/usr/lib/python3/dist-packages/synapse/storage/database.py", line 653, in simple_insert_txn
    txn.execute(sql, vals)
  File "/usr/lib/python3/dist-packages/synapse/storage/database.py", line 210, in execute
    self._do_execute(self.txn.execute, sql, *args)
  File "/usr/lib/python3/dist-packages/synapse/storage/database.py", line 236, in _do_execute
    return func(sql, *args)
psycopg2.IntegrityError: duplicate key value violates unique constraint "local_media_repository_thumbn_media_id_thumbnail_width_thum_key"
DETAIL:  Key (media_id, thumbnail_width, thumbnail_height, thumbnail_type)=(pwJGenkxEQAsZUFtmdCjriRH, 32, 32, image/png) already exists.

[anoadragon453]

Context: #2182 (comment)

[532910]

update to 1.17.0-1~bpo10+ didn't change anything

[richvdh]

fixed by #7124.

[532910]

Still see this issue on 1.19.1-1~bpo10+2 debian stable. Should it be fixed there?

[erikjohnston]

No, unfortunately it also looks like it won't be in v1.20 either, as that release is taking forever to get out of RC. Should be in v1.21 though.

[532910]

It looks like this is fixed. Anyway I don't see this error more.