{} {} encountered while building the effective model for {}

Error message

{} {} encountered while building the effective model for {} during {} (use -X to see details)

What it means

Same condition as the detailed variant, logged when debug output is disabled (a normal mvn run): while reading an artifact descriptor, model building for that dependency's POM hit problems, but an effective model was still produced. Maven summarizes the count and the phase, and points you to -X for the details. It is a warning, not a failure: resolution proceeds with the recovered model.

Source

Thrown at compat/maven-resolver-provider/src/main/java/org/apache/maven/repository/internal/DefaultArtifactDescriptorReader.java:257

                    List<ModelProblem> problems = modelResult.getProblems();
                    if (logger.isDebugEnabled()) {
                        String problem = (problems.size() == 1) ? "problem" : "problems";
                        String problemPredicate = problem + ((problems.size() == 1) ? " was" : " were");
                        StringBuilder message = new StringBuilder(String.format(
                                "%s %s encountered while building the effective model for %s during %s\n",
                                problems.size(),
                                problemPredicate,
                                request.getArtifact(),
                                RequestTraceHelper.interpretTrace(true, request.getTrace())));
                        message.append(StringUtils.capitalizeFirstLetter(problem));
                        for (ModelProblem modelProblem : problems) {
                            message.append(String.format(
                                    "\n* %s @ %s",
                                    modelProblem.getMessage(), ModelProblemUtils.formatLocation(modelProblem, null)));
                        }
                        logger.warn(message.toString());
                    } else {
                        logger.warn(
                                "{} {} encountered while building the effective model for {} during {} (use -X to see details)",
                                problems.size(),
                                (problems.size() == 1) ? "problem was" : "problems were",
                                request.getArtifact(),
                                RequestTraceHelper.interpretTrace(false, request.getTrace()));
                    }
                }
                model = modelResult.getEffectiveModel();
            } catch (ModelBuildingException e) {
                for (ModelProblem problem : e.getProblems()) {
                    if (problem.getException() instanceof UnresolvableModelException unresolvableModelException) {
                        result.addException(unresolvableModelException);
                        throw new ArtifactDescriptorException(result);
                    }
                }
                invalidDescriptor(session, trace, a, e);
                if ((getPolicy(session, a, request) & ArtifactDescriptorPolicy.IGNORE_INVALID) != 0) {
                    return null;

View on GitHub (pinned to e4093d4e12)

Solutions

Re-run with -X to switch to the detailed message listing each problem and its POM location.
Identify the artifact named in the message and check its POM (parent, imports) with mvn help:effective-pom on a copy, or open it in the local repository under ~/.m2/repository.
Fix by pinning a different version in dependencyManagement, excluding the dependency, or fixing its parent chain if you own it.
Clear a possibly corrupted local copy with mvn dependency:purge-local-repository -DreResolve=true (or delete that path) and retry with -U.

Example fix

# before
mvn install
# after
mvn install -X   # shows each '* <problem> @ <pom location>' line for the artifact named in the warning

Defensive patterns

Strategy: validation

Validate before calling

mvn -q dependency:resolve -Dmaven.wagon.http.retryHandler.count=3 >/dev/null && echo 'resolvable'

Prevention

Treat any 'problems were encountered' warning as debt: rerun -X once and file the offending POM
Keep mirrors/proxies complete: verify the full parent chain downloads for new dependencies
Purge suspect artifacts from the local repo rather than working around warnings

When it happens

Trigger: Default (non-debug) run resolving a dependency whose POM has model problems: unresolvable parent, bad dependencyManagement import, or invalid elements tolerated by lenient validation. Fired from DefaultArtifactDescriptorReader during dependency resolution or artifact descriptor load.

Common situations: Broken or partially published third-party POMs in corporate proxies; snapshot POMs with parents that were never installed; repository corruption after interrupted downloads; builds that work at work but fail behind restricted mirrors.

Related errors

AI-assisted analysis of apache/maven@e4093d4e12 (2026-08-21). Data as JSON: /api/errors/c86b42ffc0b23e94. Report an issue: GitHub.