no "charset_map" between the charsets "iso-8859-1" and "utf-8"

I have one guy that can’t accept an invite in Sogo.

mailcowdockerized-nginx-mailcow-1 | 2022/07/07 19:45:51 [error] 25#25: *3031083 no “charset_map” between the charsets “iso-8859-1” and “utf-8” while reading response header from upstream, client: 0.0.0.0, server: mail.domain.com, request: “POST /SOGo/so/user@domain.com/Mail/0/folderINBOX/171/3/Untitled-3.ics/accept HTTP/2.0”, upstream: “http://172.22.1.248:20000/SOGo/so/user@domain.com/Mail/0/folderINBOX/171/3/Untitled-3.ics/accept”, host: “mail.domain,com”, referrer: “https://mail.domain.com/”