Content Monitor I fill it out than hit save, I get this and it happening with all my DEV plugins

All of DEV plugin are giving me this

When I start to use all DEV plugin I get this:

for example, Content Monitor I fill it out than hit save, I get this

Permission Denied
Not Found / No Access

The page you are looking for either does not exist, or you do not have the permissions to access it.

Please help