Trying to open network admin dashboard url directly from the address bar shows 502 bad gateway error.
But if I try to open any other urls (e.g. plugins page) directly, it loads correctly.
This happens only when Stream plugin is network activated.
Also, I see this error in error logs when I get 502 bad gateway error:
[Wed Aug 27 23:27:09 2014] [error] [client 188.8.131.52] Request exceeded the limit of 10 internal redirects due to probable configuration error. Use 'LimitInternalRecursion' to increase the limit if necessary. Use 'LogLevel debug' to get a backtrace.