apache/maven · error · IOException

Problem during inlining POM

Error message

Problem during inlining POM

What it means

A wrapper IOException thrown by PomInlinerTransformer when streaming-parsing the raw pom.xml fails with an XMLStreamException. The root cause (line/column and XML error) is attached; it means the file being read as XML is malformed at the point read() stopped.

Source

Thrown at impl/maven-core/src/main/java/org/apache/maven/internal/transformation/impl/PomInlinerTransformer.java:140

                if (version == null && model.getParent() != null) {
                    version = model.getParent().getVersion();
                }
                String newVersion;
                if (version != null) {
                    HashSet<String> usedProperties = new HashSet<>();
                    newVersion = interpolator.interpolate(version.trim(), property -> {
                        if (!session.getConfigProperties().containsKey(property)) {
                            throw new IllegalArgumentException("Cannot inline property " + property);
                        }
                        usedProperties.add(property);
                        return (String) session.getConfigProperties().get(property);
                    });
                    if (!Objects.equals(version, newVersion)) {
                        needsInlining(session).addAll(usedProperties);
                    }
                }
            } catch (XMLStreamException e) {
                throw new IOException("Problem during inlining POM", e);
            }
        }
    }
}

View on GitHub (pinned to e4093d4e12)

Solutions

1. Open the cause chain: the nested XMLStreamException names the line and column of the XML error — fix pom.xml there
2. Check for merge-conflict markers (<<<<<<< / >>>>>>>) if the file came out of a failed merge
3. Validate the file in an editor/IDE XML parser before rebuilding
4. Ensure the file encoding matches the XML declaration

Example fix

<!-- before: pom.xml with an unclosed tag -->
<dependency>
  <groupId>org.acme</groupId>
  <artifactId>lib</artifactId>

<!-- after -->
<dependency>
  <groupId>org.acme</groupId>
  <artifactId>lib</artifactId>
</dependency>

// pre-parse the POM before running the pipeline
try (XMLInputFactory f = XMLInputFactory.newInstance(); var r = f.createXMLStreamReader(Files.newInputStream(pom))) {
    while (r.hasNext()) r.next(); // throws on malformed XML
}

catch (IOException e) {
    if ("Problem during inlining POM".equals(e.getMessage()) && e.getCause() instanceof XMLStreamException xse) {
        // fix pom.xml at the location reported by xse.getLocation()
    }
}

When it happens

Trigger: install/deploy (with consumer POM off) on a project whose pom.xml contains malformed XML: unclosed tags, stray characters, wrong encoding declaration, or a file truncated by a merge conflict. read(project.getFile().toPath()) throws XMLStreamException, which is caught and rethrown as IOException('Problem during inlining POM', e).

Common situations: Unresolved git merge conflicts left conflict markers in pom.xml; hand-editing the POM and breaking a tag; encoding mismatch (BOM/UTF-16 vs declared UTF-8); CI cache writing a partial file.

Related errors

• Unable to write model:
• Unable to write plugin:
• Unable to write settings: {}
• Unable to write toolchains: {}
• Cannot read metadata from '{}': {}

AI-assisted analysis of apache/maven@e4093d4e12 (2026-08-21). Data as JSON: /api/errors/32458add19fa3fde. Report an issue: GitHub.