Java version problemsAppClassLoader cannot be cast to URLClassLoader
What the log looks like
classloaders\$appclassloader cannot be cast to[^\n]{0,40}urlclassloader
appclassloader cannot be cast to[^\n]{0,30}java\.net\.url
How to fix it
- Old Forge (1.12.2 and earlier) only runs on Java 8
- Java 9 changed the class loader, which is exactly what this message reports
- Install Java 8 and point the instance at it
| Loaders | Forge |
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| Severity | Stops the game |
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| Category | Java version problems |
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Check your own log
