HTTP 503 Error When Deploying Java App

I am using Reclaim Cloud to test out a Java app (not one I developed). Unfortunately every time I deploy it, I get a message saying “Error 503 Service Unavailable”. My process is simple. I create an application server running Jetty 11.0.2 and OpenJDK 11.0.11 as well as a build node running Maven 3.8.1 and the same version of Java. I add the project from its Github repo, build it, and deploy the .WAR file to the application server (usually in a context called “order” or “import”). But when I navigate there in the browser all I get is the aforementioned error.

The problem is not the app. Several people have told me they have it running on Linux servers (using OpenJDK 11) and I was able to install Jetty and Maven on my Windows 10 laptop and successfully use the app. However it won’t work on Reclaim Cloud for some reason. Am I missing something? The only clue seems to be this line from the log file:

2021-05-11 20:44:50.512:WARN :oejw.WebAppContext:Scanner-0-1: Failed startup of context o.e.j.w.WebAppContext@e059fd{order,/order,file:///opt/jetty/work/jetty-0_0_0_0-80-order_war-_order-any-/webapp/,UNAVAILABLE}{/opt/jetty/webapps/order.war}

Someone also mentioned a potential problem with the JAVA_HOME variable in the Jetty start up script, but I can’t seem to find it. Any tips would be much appreciated.

It turns out the app in question is not compatible with Jetty 11.