收到错误java.lang.ClassNotFoundException：AppLoader

Question

I am using custom app loader.

play.application.loader="AppLoader"

I am getting java.lang.ClassNotFoundException: AppLoader error in my play application. The application was working fine earlier.

Stacktrace

! @78am4d92i - Internal server error, for (GET) [/] ->

play.api.PlayException: Cannot load play.application.loader[play.application.loader [AppLoader] was not loaded.]
    at play.utils.Reflect$.loadClass$1(Reflect.scala:111)
    at play.utils.Reflect$.configuredClass(Reflect.scala:124)
    at play.api.ApplicationLoader$.apply(ApplicationLoader.scala:73)
    at play.core.server.DevServerStart$$anon$1.$anonfun$reload$3(DevServerStart.scala:173)
    at play.utils.Threads$.withContextClassLoader(Threads.scala:21)
    at play.core.server.DevServerStart$$anon$1.reload(DevServerStart.scala:171)
    at play.core.server.DevServerStart$$anon$1.get(DevServerStart.scala:124)
    at play.core.server.AkkaHttpServer.handleRequest(AkkaHttpServer.scala:189)
    at play.core.server.AkkaHttpServer.$anonfun$createServerBinding$1(AkkaHttpServer.scala:106)
    at akka.stream.impl.fusing.MapAsync$$anon$25.onPush(Ops.scala:1194)
Caused by: java.lang.ClassNotFoundException: AppLoader
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    at play.utils.Reflect$.loadClass$1(Reflect.scala:105)
    at play.utils.Reflect$.configuredClass(Reflect.scala:124)
    at play.api.ApplicationLoader$.apply(ApplicationLoader.scala:73)
    at play.core.server.DevServerStart$$anon$1.$anonfun$reload$3(DevServerStart.scala:173)
    at play.utils.Threads$.withContextClassLoader(Threads.scala:21)
    at play.core.server.DevServerStart$$anon$1.reload(DevServerStart.scala:171)
    at play.core.server.DevServerStart$$anon$1.get(DevServerStart.scala:124)
[error] application - 

Answer 1

My issue was I was not referencing the class correctly. My previous code referenced the class in application.conf as play.application.loader="AppLoader" . Later I moved AppLoader in a package app but I forgot to change the entry in application.conf . I had to change it to play.application.loader="app.AppLoader"