Antony

same issue with 18.09.7, using overlay network after restart ``` docker: Error response from daemon: network sandbox join failed: network sandbox join failed: could not get network sandbox (oper true):...

I am experiencing the same issue too ... just testing with a single thread at the moment.

Not sure if it helps anyone but my issue was related to not having a cookie for the client upgrade request, sent to system under test. If your system under...

ditto, how is attachment meant to be used?

That is a great suggestion @seanmuth ! thx