Proxmox /etc/pve/nodes/node/qemu-server/ read-only after removing a node from a cluster

Problem:

After removing a node from a Proxmox cluster, the node that remains active, the cluster is left in non-operational status: you can not create virtual machines, the machine deletion fails, you can not unblock the machines, the file systems /etc/ pve is in a read-only state and many more problems.
  This is because in a cluster of 2 nodes, you have 2 votes defined (server) to access the quorum and since only one server is active one, the quorum enters a read-only state.

 

Workaround:

For a two node cluster execute the command:

After the execution of the command you can already do the usual operations like create delete unblock etc. etc.,

Final solution

Activate the second node.

Reference:

https://pve.proxmox.com/wiki/Proxmox_VE_2.0_Cluster#Two_nodes_cluster_and_quorum_issues