work

software/proftpd/proftpd-config-file.cfg.in

 ServerName "ProFTPD SlapOS"
 ServerType standalone
-DefaultServer on
 MaxInstances  30
 DefaultAddress {{ proftpd['ipv6'] }} {{ proftpd['ipv4']}}
 SocketBindTight on
+DefaultServer off
 Port {{ proftpd['sftp-port'] }}
 
 User {{ proftpd['user'] }}
@@ -34,6 +34,7 @@ AuthUserFile {{ proftpd['auth-user-file'] }}
 # Prevent partially uploaded files to be visible
 HiddenStores on
 DeleteAbortedStores on
+AllowStoreRestart off
 
 
 # Limitations of running as non-root user