Having problem starting the on-premise.

Hello,

I wanted to upgrade my on-premise Appian version from 21.1 to 21.2.

But after trying to upgrade, 

I started Appian, (https://docs.appian.com/suite/help/21.1/Starting_and_Stopping_Appian.html#starting-the-application-suite-on-linux)

and keep getting the screen like the picture bellow.

From the logs I found an ERROR message like bellow.

[download-stats-gateway] ERROR com.appian.komodo.gateway.handler.RemoteBootstrapHandler - error occurred in [id: 0x2ef44e3f, L:/127.0.0.1:5010 - R:/127.0.0.1:51388]  due to: the connection is lost by the other side

How can I solve this? I really need to fix it fast!!

Thank you!!