Once you've unsuccessfully tried to delete a namespace with ip netns delete,
it clears read permission from corresponding entry of /var/run/netns/ causing "seting the network namespace failed: Invalid argument" when namespace is used in further operations
This link provides further explanation of the issue: https:/ /bugzilla. redhat. com/show_ bug.cgi? id=872689
Once you've unsuccessfully tried to delete a namespace with ip netns delete,
it clears read permission from corresponding entry of /var/run/netns/ causing "seting the network namespace failed: Invalid argument" when namespace is used in further operations