Trying to troubleshoot why one particular mikrotik of mine will not establish a vpn or be able to recieve a request from one, just shows the TCP connection in the log hitting the router. When I checked the logs I noticed "secret string is empty? Its an older rb450g
It is running 6.47
I can only imagine that during startup, the IPsec stack crashes on a configuration (/ip ipsec identity) item which is inconsistent (auth-method=pre-shared-key, but no secret value specified, maybe thanks to some failure during configuration conversion from previous version during upgrade). So check the configuration for existence of such row(s) in /ip ipsec identity; if you find any, fix it (setting the secret to any random string will do for the purpose of dealing with the issue), and reboot the router again.
If that doesn’t help, follow my automatic signature here below.