can't run main server

[GR Techno]

Hello everyone,

When I try to run the main server its giving me this error:

$ dev_appserver.sh --port=8888 --address=0.0.0.0 appengine/build/war/

java.lang.NullPointerException
    at java.util.Objects.requireNonNull(Objects.java:203)
    at java.util.Arrays$ArrayList.<init>(Arrays.java:3813)
    at java.util.Arrays.asList(Arrays.java:3800)
    at com.google.appengine.tools.info.SdkInfo.getJetty9SharedLibFiles(SdkInfo.java:355)
    at com.google.appengine.tools.info.SdkInfo.determineSharedLibFiles(SdkInfo.java:361)
    at com.google.appengine.tools.info.SdkInfo.getSharedLibFiles(SdkInfo.java:136)
    at com.google.appengine.tools.info.SdkInfo.getSharedLibs(SdkInfo.java:128)
    at com.google.appengine.tools.info.ClassicSdk.getSharedLibs(ClassicSdk.java:113)
    at com.google.appengine.tools.development.DevAppServerClassLoader.newClassLoader(DevAppServerClassLoader.java:57)
    at com.google.appengine.tools.development.DevAppServerFactory.doCreateDevAppServer(DevAppServerFactory.java:342)
    at com.google.appengine.tools.development.DevAppServerFactory.createDevAppServer(DevAppServerFactory.java:301)
    at com.google.appengine.tools.development.DevAppServerMain$StartAction.apply(DevAppServerMain.java:383)
    at com.google.appengine.tools.util.Parser$ParseResult.applyArgs(Parser.java:45)
    at com.google.appengine.tools.development.DevAppServerMain.run(DevAppServerMain.java:257)
    at com.google.appengine.tools.development.DevAppServerMain.main(DevAppServerMain.java:248)

I'm using Java 8 (openjdk) on Ubuntu 19.04 with the last app engine (appengine-java-sdk-1.9.76).

I have no problem at all with the build server.

Please help.

Guillaume