@Mart: the hostkey is checked only at the beginning of the connection. Even if it does change in the middle of the connection (imo impossible for common OpenSSH server), you wouldn't notice the change. Something does not match in your post. Also, isn't your server load balanced? If it is, you can list hostkeys of all server instances in the -hostkey switch. If you need out help, please post logs.

Care about security or not. It just won't work otherwise so security be damned. That's because there is a bug in centos which changes host key every so often. And Centos.org won't admit it, every idiot on net just blabes about how there is some fake server in my network - there is not, host key changes even on direct connection between two computers in the middle of transmission.

Warning to others: Do not bypass host key verification using -hostkey=*, unless you do not care about security.
See also
https://winscp.net/eng/docs/scripting#hostkey
https://winscp.net/eng/docs/faq_hostkey

@Xijamk -hostkey=* solved my problem, many thanks!

I found the solution to my problem : -hostkey=*

I don't want to pass the -hostkey command with the fingerprint. I want to accept the new hostkey every time.

Hi, is there a way to accept any hostkey in command line? Because I'm trying to run this script but i'm always receiving the same message :

If you trust this host, press Yes. To connect without adding host key to the cache, press No. To abandon the connection press Cancel.
(Y)es, (N)o, C(a)ncel, (C)opy Key: Cancel

I always want to select "Y". This is because the hostkey are always changing.

Yes, I have checked https://winscp.net/eng/docs/faq_scheduler and hostkey documentation but I can't found what I need.

Thanks!