Cannot load play.http.errorHandler

Question

I'm using Play in Scala to develop a website. I've added the following line to my application.conf file in order to include the default error handling:

play.http.errorHandler = play.api.http.HtmlOrJsonHttpErrorHandler

I've done this by advice of the official documentation. However, when I add this line I get the following error:

play.api.PlayException: Cannot load play.http.errorHandler[play.http.errorHandler [play.api.http.HtmlOrJsonHttpErrorHandler] was not loaded.]
at play.utils.Reflect$.loadClass$1(Reflect.scala:111)
at play.utils.Reflect$.configuredClass(Reflect.scala:124)
at play.utils.Reflect$.bindingsFromConfiguration(Reflect.scala:50)
at play.api.http.HttpErrorHandler$.bindingsFromConfiguration(HttpErrorHandler.scala:54)
at play.api.inject.BuiltinModule$$anonfun$$lessinit$greater$1.$anonfun$new$2(BuiltinModule.scala:85)
at play.api.inject.BuiltinModule$$anonfun$$lessinit$greater$1.$anonfun$new$1(BuiltinModule.scala:35)
at scala.collection.TraversableLike.$anonfun$flatMap$1(TraversableLike.scala:241)
at scala.collection.IndexedSeqOptimized.foreach(IndexedSeqOptimized.scala:32)
at scala.collection.IndexedSeqOptimized.foreach$(IndexedSeqOptimized.scala:29)
at scala.collection.mutable.WrappedArray.foreach(WrappedArray.scala:38)
Caused by: java.lang.ClassNotFoundException: play.api.http.HtmlOrJsonHttpErrorHandler
    at java.net.URLClassLoader.findClass(URLClassLoader.java:382)
    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.utils.Reflect$.bindingsFromConfiguration(Reflect.scala:50)
    at play.api.http.HttpErrorHandler$.bindingsFromConfiguration(HttpErrorHandler.scala:54)
    at play.api.inject.BuiltinModule$$anonfun$$lessinit$greater$1.$anonfun$new$2(BuiltinModule.scala:85)
    at play.api.inject.BuiltinModule$$anonfun$$lessinit$greater$1.$anonfun$new$1(BuiltinModule.scala:35)
    at scala.collection.TraversableLike.$anonfun$flatMap$1(TraversableLike.scala:241)

Here is a screenshot of what I get when I go to localhost:

Any idea why this might be happening and how to fix it?

HtmlOrJsonHttpErrorHandler is available starting Play 2.7. Which version of Play are you using? — Mario Galic
– Mario Galic, Commented Jul 5, 2020 at 17:29
Where can I easily see this? I tfound this in the build.sbt file version = 2.6.x. — Astarno
– Astarno, Commented Jul 5, 2020 at 18:20
I've also found this link: playframework.com/documentation/2.4.x/ScalaErrorHandling which is an earlier version and there they use a default error handler as well. — Astarno
– Astarno, Commented Jul 5, 2020 at 18:32

Mario Galic · Accepted Answer · 2020-07-05 18:36:56Z

3

Comparing changes between Play 2.6.25 and 2.7.0 we deduce that HtmlOrJsonHttpErrorHandler was introduced by Add an HttpErrorHandler that selects the client's preferred media type #8540. The version of Play used in your project should be specified under project/plugins.sbt as something like

addSbtPlugin("com.typesafe.play" % "sbt-plugin" % "2.6.0")

If you are using 2.6.0 then follow the migration guide to 2.7.

answered Jul 5, 2020 at 18:36

Mario Galic

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3 Comments

Astarno Over a year ago

Are u sure the problem lays with HtmlOrJsonHttpErrorHandler and not with play.http.errorHandler? To my understanding, this line should work in Play 2.6 play.http.errorHandler = DefaultHttpErrorHandler, however, it returns the same error.

Astarno Over a year ago

I have addSbtPlugin("com.typesafe.play" % "sbt-plugin" % "2.6.19") by the way, I just verified. If I can just find a way to introduce some default error handing using this version I think that would be better than migrating to 2.7.

Mario Galic Over a year ago

@Arno You have to provide fully qualified name to error handler play.http.errorHandler = play.api.http.DefaultHttpErrorHandler.

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