I have same issue after upgrading Erlang from 25.2.1 to version 26.2
I'm able to connect to management portal. But none of CLI tools are working.

Cookies were checked (user, service account) use the same. Also I'm seeing same hash value in RabbitMQ logs and after executing rabbitmqctl.

Also nodes are not able to communicate each other-i have cluster of three. But now I have three standalone.