IPSec tunnel flapping due to "peer address change is not allowed"

RouterOS Beginner Basics
1

Hello all,

I tried to upgrade different RB with IPSec VPN to 7.20.7 (Long-Term).

The problem is that, after the upgrade, all the IPSec tunnel frequently flaps and I see on the logs the following message:

“ipsec,error peer address change is not allowed at this moment”

Have you ever had this problem?

Note that all the IP Addresses that the sites use to establish the tunnels are public and static.

I have never seen this with RouterOS 6.x.

Thank you