apache/maven · error · MavenExecutionException

Could not find the selected project in the reactor: {}

Error message

Could not find the selected project in the reactor: {}

What it means

Deprecated (since 4.0.0) variant of project-selection failure: getRequiredProjectsBySelectors() throws immediately when a selector resolves to no reactor project. Unlike the newer getActiveProjects, there is no optional/required distinction and no batching of unmatched selectors. Matching rules are identical: ':artifactId', 'groupId:artifactId', or a path relative to the base directory (file or directory match).

Source

Thrown at impl/maven-core/src/main/java/org/apache/maven/graph/ProjectSelector.java:101

        return resolvedOptionalProjects;
    }

    /**
     * @deprecated use {@link #getActiveProjects(MavenExecutionRequest, List, List)}
     */
    @Deprecated(since = "4.0.0")
    public Set<MavenProject> getRequiredProjectsBySelectors(
            MavenExecutionRequest request, List<MavenProject> projects, Set<String> projectSelectors)
            throws MavenExecutionException {
        Set<MavenProject> selectedProjects = new LinkedHashSet<>();
        File baseDirectory = getBaseDirectoryFromRequest(request);
        for (String selector : projectSelectors) {
            Optional<MavenProject> optSelectedProject =
                    findOptionalProjectBySelector(projects, baseDirectory, selector);
            if (!optSelectedProject.isPresent()) {
                String message = "Could not find the selected project in the reactor: " + selector;
                throw new MavenExecutionException(message, request.getPom());
            }

            MavenProject selectedProject = optSelectedProject.get();

            selectedProjects.add(selectedProject);
            selectedProjects.addAll(getChildProjects(selectedProject, request));
        }

        return selectedProjects;
    }

    /**
     * @deprecated use {@link #getActiveProjects(MavenExecutionRequest, List, List)}
     */
    @Deprecated(since = "4.0.0")
    public Set<MavenProject> getOptionalProjectsBySelectors(
            MavenExecutionRequest request, List<MavenProject> projects, Set<String> projectSelectors) {
        Set<MavenProject> resolvedOptionalProjects = new LinkedHashSet<>();

View on GitHub (pinned to e4093d4e12)

Solutions

1. Fix the selector to match a reactor module (':artifactId' form is most robust)
2. Run from the reactor root so path selectors resolve
3. Migrate calling code to getActiveProjects(request, projects, activations), which distinguishes optional selectors
4. Enable profiles required for the target module to be in the reactor

Example fix

// before: legacy call with a bad selector
selector.getRequiredProjectsBySelectors(request, projects, Set.of(":nope"));

// after: modern API with explicit activations
selector.getActiveProjects(request, projects, activationList);

// Pre-check each selector the way the deprecated method matches
Optional<MavenProject> hit = projects.stream()
    .filter(p -> (":" + p.getArtifactId()).equals(selector)
              || (p.getGroupId() + ":" + p.getArtifactId()).equals(selector)
              || pathMatches(p, selector, baseDirectory))
    .findFirst();
if (hit.isEmpty()) throw new IllegalArgumentException("No reactor project for selector: " + selector);

try {
    selected = selector.getRequiredProjectsBySelectors(request, projects, selectors);
} catch (MavenExecutionException e) {
    if (e.getMessage().startsWith("Could not find the selected project")) {
        // selector typo: extract and report, then continue with remaining selectors
        log.warn("Skipping unmatched selector: {}", e.getMessage());
        selected = Collections.emptySet();
    } else throw e;
}

When it happens

Trigger: Calling ProjectSelector.getRequiredProjectsBySelectors(...) directly (or via legacy graph-builder paths) with a selector matching no project's artifactId/groupId combination or basedir/pom file under the request's base directory.

Common situations: Custom tooling or old Maven forks still routing through the deprecated selector; same root causes as the modern variant: typos, wrong working directory, or modules excluded from the reactor.

Related errors

• The project exclusion%s in --projects/-pl resulted in an emp
• The requested required projects {} do not exist.
• Two or more projects in the reactor have the same identifier
• Invalid reactor make behavior: {}
• Edge between '{}' and '{}' introduces to cycle in the graph

AI-assisted analysis of apache/maven@e4093d4e12 (2026-08-21). Data as JSON: /api/errors/9fa84e004b80b33c. Report an issue: GitHub.