I just setup a test installation for Magento2 using Varnish 3. All seems to work fine but one thing is really strange:
If i register a new account i got the messages box telling me "Thank you for registering with Main Website Store.". This is fine on the first redirect, when registration is completed. But it always is showing up on any page.
The div container with class "page messages" is still getting delievered to the browser.
I used the default.vcl from the Magento backend, copied it to /etc/varnish/default.vcl (as this file is used by starting varnish). Is there anything else to do like the old -p esi_syntax=0x2 and cli_buffer? I used em both, but still i got this messages.
EDIT: I have opened a new browser incognito window and out of sudden in the incognito window i can't reproduce this 'error'. But still happening in the normal window, which wasn't closed all the time.