my fault, https://www.elastic.co/guide/en/beats/filebeat/7.6/configuration-filebeat-options.html
says:
To configure Filebeat manually (instead of using modules), you specify a list of inputs in the filebeat.inputs section of the filebeat.yml . Inputs specify how Filebeat locates and processes input data.
So. I've deleted netflow input definition from filebeat.inputs infilebeat.yml and evething works fine.
Sorry.