Play 1.2.x UnexpectedException ContinuationEnhancer on helpers.CheatSheetHelper $ 2 invalid constant type: 15

Question

Play framework 1.2.x starts with the following error:

Oops: UnexpectedException An unexpected error occured caused by exception UnexpectedException: While applying class play.classloading.enhancers.ContinuationEnhancer on helpers.CheatSheetHelper$2 play.exceptions.UnexpectedException: While applying play.CorePlugin@3444d69d on helpers.CheatSheetHelper$2 at play.plugins.PluginCollection.enhance(PluginCollection.java:556) at play.classloading.ApplicationClasses$ApplicationClass.enhance(ApplicationClasses.java:235) at play.classloading.ApplicationClassloader.loadApplicationClass(ApplicationClassloader.java:167) at play.classloading.ApplicationClassloader.getAllClasses(ApplicationClassloader.java:431) at play.Play.preCompile(Play.java:600) at play.Play.init(Play.java:304) at play.server.Server.main(Server.java:162) Caused by: play.exceptions.UnexpectedException: While applying class play.classloading.enhancers.ContinuationEnhancer on helpers.CheatSheetHelper$2 at play.CorePlugin.enhance(CorePlugin.java:302) at play.plugins.PluginCollection.enhance(PluginCollection.java:551) ... 6 more Caused by: java.lang.RuntimeException: java.io.IOException: invalid constant type: 15 at javassist.CtClassType.getClassFile2(CtClassType.java:203) at javassist.CtClassType.subtypeOf(CtClassType.java:303) at javassist.CtClassType.subtypeOf(CtClassType.java:318) at play.classloading.enhancers.ContinuationEnhancer.enhanceThisClass(ContinuationEnhancer.java:49) at play.CorePlugin.enhance(CorePlugin.java:297) ... 7 more Caused by: java.io.IOException: invalid constant type: 15 at javassist.bytecode.ConstPool.readOne(ConstPool.java:1027) at javassist.bytecode.ConstPool.read(ConstPool.java:970) at javassist.bytecode.ConstPool.<init>(ConstPool.java:127) at javassist.bytecode.ClassFile.read(ClassFile.java:693) at javassist.bytecode.ClassFile.<init>(ClassFile.java:85) at javassist.CtClassType.getClassFile2(CtClassType.java:190) ... 11 more 

Answer 1

This may be due to jdk used to start playback. If you are using java8 jdk, chances are you will want to try java7. This solved the problem for me.

Answer 2

Play 1.2.5 ships with Javassist 3.9.0, which does not fully understand the bytecode generated by the JDK 8 compiler. Either compile JDK 7, or update the Javassist library in the play / lib / framework / section, for example, in Javassist 3.18.0.