With 7.8.0 and 7.8.1 there was no problems. But now ...
{
"statusCode": 405,
"error": "Method Not Allowed",
"message": "invalid escape sequence `%{[' at index 0 of: %{[@metadata][beat]}-%{[@metadata][version]}-2020.08.23,%{[@metadata][beat]}-%{[@metadata][version]}-2020.08.24,filebeat-7.9.0-2020.08.20-000001,filebeat-7.9.0-2020.08.22-000002,filebeat-7.9.0-2020.08.24-000003,logback-2020.08.16,logback-2020.08.17,logback-2020.08.18,logback-2020.08.20,logback-2020.08.23, allowed: [GET, PUT, HEAD, DELETE]"
}