hi,
I was recently asked by a friend to check if I could log in to their username and use multiplayer, they asked that the .minecraft file was created by signing into their name saying that multiplayer wouldn't work.

I've tested their theory even when turning all firewalls off and any form of real time scanning was halted to ensure no interferences were caused.

when I signed in and produced the .minecraft folder by their username they were correct, no multiplayer servers could be joint, as this was unlikely to be a single account issue I then delete the .minecraft folder and signed in as myself, this also blocked any connection to online servers with an error message being as specific as "no more information".

I then placed a .minecraft folder in my appdata which i produced under my username on the OLD launcher, this allowed me full access to multiplayer.

so;
*any new .minecraft folders produced fail to operate online
*all firewalls were turned off and the scenario retested with the same outcome
*all scans ( including real time where halted )
*internet connections were plentiful
*issue is not limited to my broadband, nor my PC
*launcher is fully up to date ( inc all windows updates + java + flash player )
i hope that this issue is resolved in due time having done all common or likely troubleshooting techniques to the same end result on multiple PC systems on different broadband connections all with different security software suppliers

thank you
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as of now both myself and the friend are using my .minecraft folder to play minecraft online.
This is a copy / paste of an email I've sent, if any further information is required from my end let me know.

other report of issue found by search ;
https://bugs.mojang.com/browse/MC-55087?jql=text%20~%20%22multiplayer%20not%20work%20with%20.minecraft%20folder%22

*i was asked by a responce email to come here to state the information also.