{"record":{"id":"e7379193b78ac619","repo":"apache/maven","slug":"an-i-o-error-occurred-while-checking-if-the-packag","errorCode":null,"errorMessage":"An I/O error occurred while checking if the packaged artifact is up-to-date against the build output directory. Continuing with the assumption that it is up-to-date.","messagePattern":"An I/O error occurred while checking if the packaged artifact is up-to-date against the build output directory\\. Continuing with the assumption that it is up-to-date\\.","errorType":"console","errorClass":null,"httpStatus":null,"severity":"warning","filePath":"impl/maven-core/src/main/java/org/apache/maven/ReactorReader.java","lineNumber":272,"sourceCode":"                    LOGGER.warn(\n                            \"File '{}' is more recent than the packaged artifact for '{}', \"\n                                    + \"please run a full `mvn package` build\",\n                            relativizeOutputFile(outputFile),\n                            project.getArtifactId());\n                    return false;\n                } else if (LOGGER.isDebugEnabled()) {\n                    LOGGER.debug(\n                            \"File '{}' timestamp {} vs artifact timestamp {} for '{}'\",\n                            relativizeOutputFile(outputFile),\n                            outputFileLastModified,\n                            artifactLastModified,\n                            project.getArtifactId());\n                }\n            }\n\n            return true;\n        } catch (IOException e) {\n            LOGGER.warn(\n                    \"An I/O error occurred while checking if the packaged artifact is up-to-date \"\n                            + \"against the build output directory. \"\n                            + \"Continuing with the assumption that it is up-to-date.\",\n                    e);\n            return true;\n        }\n    }\n\n    private boolean hasBeenPackagedDuringThisSession(MavenProject project) {\n        boolean packaged = false;\n        for (String phase : getLifecycles(project)) {\n            switch (phase) {\n                case \"clean\":\n                    packaged = false;\n                    break;\n                case \"package\":\n                case \"install\":\n                case \"deploy\":","sourceCodeStart":254,"sourceCodeEnd":290,"githubUrl":"https://github.com/apache/maven/blob/e4093d4e120eac99d6bdce5ba67cace2f3085c97/impl/maven-core/src/main/java/org/apache/maven/ReactorReader.java#L254-L290","documentation":"Warning in ReactorReader (Maven 4's mechanism that resolves inter-module dependencies from the current reactor session): while comparing the packaged artifact file's timestamp against the build output directory to decide staleness, an IOException occurred. The code deliberately degrades gracefully, assumes the artifact IS up-to-date, and returns true. Risk: a genuinely stale packaged jar can be consumed as if fresh.","triggerScenarios":"During a reactor build with the default workspace reader active, file attribute reads (Files.getLastModifiedTime / BasicFileAttributes walk of target/classes) throw IOException: unreadable target directory, permission changes, files deleted concurrently by another build/antivirus in the same tree, or exotic filesystems that fail attribute queries.","commonSituations":"Parallel builds sharing target/ directories; IDE and CLI builds racing on the same module; network file systems (NFS/SMB) with flaky attribute support; containers with read-only mounted target dirs.","solutions":["Run the build with clean (mvn clean verify) so staleness is irrelevant and artifacts are repackaged.","Check permissions/ownership of the module's target/ directory and repair if unreadable.","Stop concurrent builds sharing one checkout, or use -Dmaven.repo.local / separate workspaces per job.","Exclude target/ from antivirus scanning; avoid placing builds on flaky network mounts.","If persistent, capture the IOException stack with -X to see which file operation failed."],"exampleFix":"# before: incremental build consumes possibly stale artifact\nmvn verify\n# after: force repackaging when staleness warnings appear\nmvn clean verify","handlingStrategy":"fallback","validationCode":"# verify the reactor tree is clean and not shared before building\n[ ! -e target ] || git clean -xdn target/ # inspect what would be removed","typeGuard":null,"tryCatchPattern":null,"preventionTips":["Run mvn clean when switching branches or after aborted builds so staleness assumptions cannot bite.","One checkout per concurrent build job; never share target/ directories.","Keep builds on local filesystems, not flaky network mounts."],"tags":["maven","reactor","io","stale-artifacts","graceful-degradation"],"backgroundTag":"file-io-error-ignored","analyzedSha":"e4093d4e120eac99d6bdce5ba67cace2f3085c97","analyzedAt":"2026-08-21T22:58:24.034Z","schemaVersion":2},"datasetVersion":"2026-08-21T23:17:16.201Z"}