JetBrains/intellij-community · error · RuntimeException

Malformed exclusion, 'groupId:artifactName' format is expect

Error message

Malformed exclusion, 'groupId:artifactName' format is expected but got 

What it means

Thrown by the Maven/Aether dependency resolver when a dependency-exclusion string cannot be parsed. Each entry in the excludedDependencies list must be exactly 'groupId:artifactName'; the code splits on the first ':' and requires exactly two non-empty parts. Anything without a colon (empty string, 'artifact', 'group:art:version' with the 2-limit split still yields 2 parts, but a bare name or blank entry) fails the split.length != 2 check.

Source

Thrown at aether-dependency-resolver/src/org/jetbrains/idea/maven/aether/ArtifactRepositoryManager.java:211

          new ExclusionDependencySelector(exclusions(excludedDependencies)))
        );
      }
      session.setReadOnly();
      return session;
    }

    RepositorySystemSession createSessionCloneWithCleanData(RepositorySystemSession fromSession) {
      DefaultRepositorySystemSession newSession = new DefaultRepositorySystemSession(fromSession).setData(new DefaultSessionData());
      newSession.setReadOnly();
      return newSession;
    }

    @SuppressWarnings("SSBasedInspection")
    private static List<Exclusion> exclusions(List<String> excludedDependencies) {
      return excludedDependencies.stream().map(exclusion -> {
        String[] split = exclusion.split(":", 2);
        if (split.length != 2) {
          throw new RuntimeException("Malformed exclusion, 'groupId:artifactName' format is expected but got " + exclusion);
        }
        String groupId = split[0];
        String artifactName = split[1];
        return new Exclusion(groupId, artifactName, "*", "*");
      }).collect(Collectors.toList());
    }
 }

  /**
   * Returns list of classes corresponding to classpath entries for this module.
   */
  @SuppressWarnings("UnnecessaryFullyQualifiedName")
  public static Class<?>[] getClassesFromDependencies() {
    var result = new ArrayList<>(List.of(
      org.jetbrains.idea.maven.aether.ArtifactRepositoryManager.class, //this module
      org.apache.maven.repository.internal.VersionsMetadataGeneratorFactory.class, //maven-aether-provider
      org.apache.maven.artifact.Artifact.class, //maven-artifact
      org.apache.commons.lang3.StringUtils.class, //commons-lang3

View on GitHub (pinned to be881553f2)

Solutions

1. Correct the exclusion entry to the strict 'groupId:artifactName' form (e.g. 'junit:junit').
2. If the value comes from UI or config, trim it and validate the format before passing it to the resolver.
3. Audit the excludedDependencies list at load time and report all malformed entries at once instead of failing on the first.

Example fix

// before
List<String> excluded = List.of("junit");

// after
List<String> excluded = List.of("junit:junit");

boolean valid = !exclusion.isBlank() && exclusion.indexOf(':') > 0 && exclusion.indexOf(':') < exclusion.length() - 1;
if (!valid) throw new IllegalArgumentException("Exclusion must be 'groupId:artifactName': " + exclusion);

try { resolver.resolve(..., excludedDependencies); } catch (RuntimeException e) { if (e.getMessage().startsWith("Malformed exclusion")) reportConfigError(e.getMessage()); else throw e; }

When it happens

Trigger: Calling the resolver API with an excludedDependencies list containing an entry that has no ':' character, e.g. "", "junit", or " org.junit " (whitespace-only). Only the presence of at least one ':' matters to split(..., 2); entries like "g:a:v" parse but silently take 'a:v' as artifactName, which is a separate config smell.

Common situations: A run configuration, plugin XML, or build DSL field for Maven import exclusions is left blank (produces ""), a user types only an artifact name, or a YAML/properties value loses its colon through quoting or templating.

Understand the failure class

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

• Row %d failed: hierarchicalIdx cannot be null
• Row %d access failed: hierarchicalIdx cannot be empty
• Offset out of range (from -12:00 to +14:00)
• error.text.invalid.port
• error.jdk.not.specified

AI-assisted analysis of JetBrains/intellij-community@be881553f2 (2026-08-14). Data as JSON: /api/errors/3bea5643e5fdbf27. Report an issue: GitHub.