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UnsupportedClassVersionError with Screen-scraper 7.0

We have been trying to install SS 7.0 to our server boxes, which have been running the latest 6 alpha just fine. It seems to be having issues, however. Here's the account from my dev:

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I have installed screen-scraper 7 on a new DigitalOcean droplet from scratch, getting the shell script install source from their website. I installed Java 8. I followed the steps on their site for editing the specified files. When trying to run screen-scraper.jar, it's throwing an error.

java -jar screen-scraper.jar -s '16 Handles' Exception in thread "main" java.lang.UnsupportedClassVersionError: com/screenscraper/controller/ControllerMain : Unsupported major.minor version 52.0 at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClass(ClassLoader.java:800) at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142) at java.net.URLClassLoader.defineClass(URLClassLoader.java:449) at java.net.URLClassLoader.access$100(URLClassLoader.java:71) at java.net.URLClassLoader$1.run(URLClassLoader.java:361) at java.net.URLClassLoader$1.run(URLClassLoader.java:355) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:354) at java.lang.ClassLoader.loadClass(ClassLoader.java:425) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308) at java.lang.ClassLoader.loadClass(ClassLoader.java:358) at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:482)

The version of java is:

java -version
openjdk version "1.8.0_71"
OpenJDK Runtime Environment (build 1.8.0_71-b15)
OpenJDK 64-Bit Server VM (build 25.71-b15, mixed mode)

In the "server" and "screen-scraper" files, based on the instructions, I updated the line referencing the JRE location to

INSTALL4J_JAVA_HOME_OVERRIDE=/usr/lib/jvm/jre-1.8.0-openjdk.x86_64

The registration is set and the register_result.txt shows

more register_result.txt
Your registration is valid.  Thanks for registering!

At this point, I'm at a loss as to why the JAR file isn't working with Java 8.
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Any suggestions on what might be the problem or what to try next? He said he tried it with 1.7.0_85 as well with the same error.

‹ Input/output error for https site Unable to export Scraping Session ›
chrishathaway on 03/23/2016 at 3:21 pm

I'm not sure would be causing

I'm not sure would be causing that error. I tried running a scrape on my machine from the command line like that and it ran without any problems.

The error from the JVM is clearing indicating the JVM version isn't the correct version. The major.minor 52.0 is Java 8, which would seem to indicate the JVM you are running on is pre-Java 8. That shouldn't be the case though since the 'java -version' command shows Java 8, but that is what the error indicates.

With the 7.0 release of screen-scraper, we started building the code with Java 8 and are using some of the new classes and features available in Java 8, whereas on the latest alpha before this release the code was built on Java 6, which explains why you had no errors with the latest alpha.

Here are a few ideas I might try.

  1. Remove all other Java installs on the server so that we verify the only possible JVM it can run on is Java 8.
  2. Remove/rename the "jre" directory in screen-scraper, if present. I believe with DigitalOcean servers you won't have a jre directory as we no longer bundle the JRE for Linux, but if it is present it's possible something is still causing it to be used. When it isn't present screen-scraper will use the system JRE instead.

Please let us know if that fixed the issue or not, and if not we can look into it further.

 mikes on 03/24/2016 at 9:53 am

There was an jre folder in

There was an jre folder in screen-scraper that I removed, and I uninstalled Java 7. I checked the box to insure there were no other JREs and everything seems to be working as expected now! :)

Thanks for the help.

 chrishathaway on 03/28/2016 at 12:24 pm