Exception with Maven: Malformed \uxxxx encoding

May 27, 2021

Recently I was cleaning up some dependencies in a maven-built project. At times I would forget to create a property value with the version of a particular dependency. Seems like things were working well.

However, a couple days ago I tried to build another project and ended up with the following stacktrace--every single time I tried to build.

[ERROR] Internal error: java.lang.IllegalArgumentException: Malformed \uxxxx encoding. -> [Help 1]
org.apache.maven.InternalErrorException: Internal error: java.lang.IllegalArgumentException: Malformed \uxxxx encoding.
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:120)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:957)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:289)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:193)
    at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:498)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:282)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:225)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:406)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:347)
Caused by: java.lang.IllegalArgumentException: Malformed \uxxxx encoding.
    at java.util.Properties.loadConvert (Properties.java:574)
    at java.util.Properties.load0 (Properties.java:390)
    at java.util.Properties.load (Properties.java:341)
    at org.eclipse.aether.internal.impl.TrackingFileManager.read (TrackingFileManager.java:56)
    at org.eclipse.aether.internal.impl.DefaultUpdateCheckManager.read (DefaultUpdateCheckManager.java:511)
    at org.eclipse.aether.internal.impl.DefaultUpdateCheckManager.checkMetadata (DefaultUpdateCheckManager.java:250)
    at org.eclipse.aether.internal.impl.DefaultMetadataResolver.resolve (DefaultMetadataResolver.java:302)
    at org.eclipse.aether.internal.impl.DefaultMetadataResolver.resolveMetadata (DefaultMetadataResolver.java:181)
    at org.apache.maven.repository.internal.DefaultVersionResolver.resolveVersion (DefaultVersionResolver.java:213)
    at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolve (DefaultArtifactResolver.java:282)
    at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolveArtifacts (DefaultArtifactResolver.java:229)
    at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolveArtifact (DefaultArtifactResolver.java:207)
    at org.eclipse.aether.internal.impl.DefaultRepositorySystem.resolveArtifact (DefaultRepositorySystem.java:262)
    at org.apache.maven.project.ProjectModelResolver.resolveModel (ProjectModelResolver.java:192)
    at org.apache.maven.project.ProjectModelResolver.resolveModel (ProjectModelResolver.java:242)
    at org.apache.maven.model.building.DefaultModelBuilder.readParentExternally (DefaultModelBuilder.java:1070)
    at org.apache.maven.model.building.DefaultModelBuilder.readParent (DefaultModelBuilder.java:846)
    at org.apache.maven.model.building.DefaultModelBuilder.build (DefaultModelBuilder.java:337)
    at org.apache.maven.project.DefaultProjectBuilder.build (DefaultProjectBuilder.java:448)
    at org.apache.maven.project.DefaultProjectBuilder.build (DefaultProjectBuilder.java:414)
    at org.apache.maven.project.DefaultProjectBuilder.build (DefaultProjectBuilder.java:377)
    at org.apache.maven.graph.DefaultGraphBuilder.collectProjects (DefaultGraphBuilder.java:414)
    at org.apache.maven.graph.DefaultGraphBuilder.getProjectsForMavenReactor (DefaultGraphBuilder.java:405)
    at org.apache.maven.graph.DefaultGraphBuilder.build (DefaultGraphBuilder.java:82)
    at org.apache.maven.DefaultMaven.buildGraph (DefaultMaven.java:507)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:219)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192)
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:957)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:289)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:193)
    at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:498)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:282)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:225)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:406)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:347)
[ERROR] 
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/InternalErrorException

I tried various options, one of which was mvn -o clean install, which worked. My initial thought was that the problem had to do with the way I referenced upstream repositories in my settings.xml. However, any refactoring I did with that file did not yield positive results1.

Then I thought maybe the remote repositories were corrupted--particularly the one I host. This was highly unlikely and some tests met my expectations.

Then I started digging into the Maven source tree (e.g., DefaultUpdateCheckManager) and remembered that maven used files such as resolver-status.properties and *.lastUpdated, to keep a record of when an update needs to occur. This led to the source of the problem. When searching for such files (e,g., find ~/.m2/repository -name '*.lastUpdated), I found something like the following:

./repository/repository-repository/\org/apache/tomcat/maven/${rootArtifactId}/\3.0-SNAPSHOT/${rootArtifactId}-\3.0-SNAPSHOT.pom.lastUpdated

So the lastUpdated files were not the problem, but rather the path was bad.

I am really not sure how I ended up with a version of ${rootArtifactId}/\3.0-SNAPSHOT. 🤷

It was easy enough to remove do a find to remove the folders.

Fun times.

  1. Refactoring my settings.xml was needed anyway--e.g., passwords are now encrypted.
Tags: Maven Java