Failed to initialize language server due to "Internal error. Caused by: NPE: Cannot invoke 'o.e.m.c.e.IMaven.getSettings()' because the return value of 'o.e.m.c.MavenPlugin.getMaven()' is null" about vscode-java

[testforstephen]

From the BI logs, this issue is easier to happen when new version of vscode-java is just released. This might be related to the activation of plugin.

[testforstephen]

Latest call stack:

Caused by: java.lang.NullPointerException: Cannot invoke "org.eclipse.m2e.core.embedder.IMaven.getSettings()" because the return value of "org.eclipse.m2e.core.MavenPlugin.getMaven()" is null
	at org.eclipse.jdt.ls.core.internal.preferences.StandardPreferenceManager.update(StandardPreferenceManager.java:125)
	at org.eclipse.jdt.ls.core.internal.handlers.BaseInitHandler.handleInitializationOptions(BaseInitHandler.java:115)
	at org.eclipse.jdt.ls.core.internal.handlers.InitHandler.handleInitializationOptions(InitHandler.java:109)
	at org.eclipse.jdt.ls.core.internal.handlers.BaseInitHandler.initialize(BaseInitHandler.java:64)
	at org.eclipse.jdt.ls.core.internal.handlers.JDTLanguageServer.initialize(JDTLanguageServer.java:283)
	... 17 more

This NPE is also easier to happen for Windows than other platforms (macOS and linux).

[Eskibear]

Caused by: java.lang.NullPointerException: Cannot invoke "org.eclipse.m2e.core.embedder.IMaven.getSettings()" because the return value of "org.eclipse.m2e.core.MavenPlugin.getMaven()" is null
at org.eclipse.jdt.ls.core.internal.preferences.StandardPreferenceManager.update(StandardPreferenceManager.java:125)

Will it be auto resolved (i.e. no NPE) next time when it tries to import the Maven project? If so, is there any approach we can do in jdt.ls.core to catch the NPE and do something to mitigate the issue?

[testforstephen]

Will it be auto resolved (i.e. no NPE) next time when it tries to import the Maven project? If so, is there any approach we can do in jdt.ls.core to catch the NPE and do something to mitigate the issue?

I believe so. This NPE rate goes to a PEAK at the first week of new vscode-java release and then goes down to a lower rate. This is because most of users upgrade to new version on the first week of new release.

[testforstephen]

Add @fbricon @rgrunber, since your team is more familiar with m2e mechanism. org.eclipse.m2e.core.MavenPlugin.getMaven() returns null when activating jdt.ls.

[rgrunber]

Interesting observation (about the errors peaking during a new release). Maybe it's a case of the newer m2e invalidating some aspect of the older settings, that then gets automatically fixed ?

Happens at : StandardPreferenceManager.update(..)

Update: Seems similar to eclipse-m2e/m2e-core#966 which points to an issue with org.eclipse.core.resources. It might be related to the initial startup, that caches the Equinox dependency wiring under $HOME/.config/Code/User/globalStorage/redhat.java/${version}/config_linux/ .

The problem is somewhere at https://github.com/eclipse-m2e/m2e-core/blob/2.6.0/org.eclipse.m2e.core/src/org/eclipse/m2e/core/internal/MavenPluginActivator.java#L68-L86 -> https://github.com/eclipse-equinox/equinox/blob/R4_32_maintenance/bundles/org.eclipse.osgi/osgi/src/org/osgi/util/tracker/ServiceTracker.java#L677-L693 . I don't think the activator or the bundle context are null though there's a chance maybe the bundle context somehow might be. I think it's more likely the failure is happening somewhere in getting the registered services but not sure how.