For what it’s worth, in 2018, the docs are WRONG. In windows 10, the default location of the cookie file appears to be:
C:\Windows\System32\config\systemprofile
and NOT
C:\Windows
as the docs say.
The best thing to do is to look at the log file, which is typically located in your user %AppData%\Roaming\RabbitMQ\log
directory.
The log file contains this entry, which helped me determine the cookie location:
node : rabbit@computername
home dir : C:\WINDOWS\system32\config\systemprofile