Solution: 
I solved the problem. Everything was well configured in plugins.js and middelwares.js. The problem was being caused by modsecurity on the server. It is necessary to create a rule or disable modsecurity for that domain and problem solved.
Solution:
I solved the problem. Everything was well configured in plugins.js and middelwares.js. The problem was being caused by modsecurity on the server. It is necessary to create a rule or disable modsecurity for that domain and problem solved.