Problem restoring backups to new Server

Hi,

Ubuntu 18.04 fresh install
webmin 1.900
virtualmin 6.04

I have some issue with restoring backup

I cannot restore any virtual server backups and miniserv.error logs returned:

/webmin/install_mod.cgi : Timeout : Waited more than 60 seconds for request data

But I can restore backup manually from the command line

Backup source:
Ubuntu 14.04.3 / Webmin 1.890 / Virtualmin 6.03

Also the same error log shows when I am trying to install new webmin modules (pptp-client )

Any ideas ?
thank you

ifan

Update:

turned out its a browser issue… (Safari 11.1.2)
tried using Firefox : restore backup and install modules are working