What causes "Failed to parse ${extensionFile}" in quarkusio/quarkus?

Verify the extensionFile path exists and is readable (ls the exact path printed)

quarkusio/quarkus · error · MojoExecutionException

Failed to parse ${extensionFile}

Error message

Failed to parse ${extensionFile}

What it means

readExtensionDescriptorFile reads the external extension descriptor file (extensionFile parameter) with Jackson into an ObjectNode. Any IOException — file missing, unreadable, or malformed JSON — is wrapped in a MojoExecutionException naming the file path, so the developer sees "Failed to parse <path>".

Source

Thrown at independent-projects/extension-maven-plugin/src/main/java/io/quarkus/maven/ExtensionDescriptorMojo.java:624

        }
        if (artifactNode == null || groupId == null || artifactId == null || version == null) {
            final ArtifactCoords coords = ArtifactCoords.jar(
                    groupId == null ? project.getGroupId() : groupId,
                    artifactId == null ? project.getArtifactId() : artifactId,
                    version == null ? project.getVersion() : version);
            extObject.put("artifact", coords.toString());
        }
    }

    private static String getRealValueOrNull(String s, String propertyExpr) {
        return s != null && !s.isBlank() && !s.equals(propertyExpr) ? s : null;
    }

    private ObjectNode readExtensionDescriptorFile(Path extensionFile, ObjectMapper mapper) throws MojoExecutionException {
        try (InputStream is = Files.newInputStream(extensionFile)) {
            return mapper.readValue(is, ObjectNode.class);
        } catch (IOException io) {
            throw new MojoExecutionException("Failed to parse " + extensionFile, io);
        }
    }

    private void completeCodestartArtifact(ObjectMapper mapper, ObjectNode extObject) throws MojoExecutionException {
        JsonNode mvalue = getJsonElement(extObject, METADATA, "codestart");
        if (mvalue == null || !mvalue.isObject()) {
            return;
        }
        final ObjectNode codestartObject = (ObjectNode) mvalue;
        mvalue = mvalue.get("artifact");
        if (mvalue == null) {
            if (!skipCodestartValidation) {
                throw new MojoExecutionException("Codestart artifact is missing from the " + extensionFile);
            }
            return;
        }

        String codestartArtifact = getCodestartArtifact(mvalue.asText(), project.getVersion());

View on GitHub (pinned to e1c734241f)

Solutions

Verify the extensionFile path exists and is readable (ls the exact path printed)
Validate the JSON content (jq . extension.json) and fix syntax errors
Check the wrapped IOException cause — FileNotFoundException vs JsonParseException — to distinguish path vs content problems

Example fix

// before: extension.json with trailing comma
{ "name": "myext", }
// after
{ "name": "myext" }

Defensive patterns

Strategy: validation

Validate before calling

Path f = Paths.get(configuredExtensionFile);
if (!Files.isReadable(f)) throw new IllegalStateException("extensionFile unreadable: " + f);
try (InputStream is = Files.newInputStream(f)) {
  new ObjectMapper().readTree(is); // throws if JSON is malformed
}

Try / catch

try {
  invoker.executeMaven("extension-descriptor");
} catch (MojoExecutionException e) {
  if (e.getMessage().startsWith("Failed to parse ")) { validateAndRepairJson(); }
  throw e;
}

Prevention

jq-validate extension.json before running the goal
Use absolute paths for extensionFile or paths relative to the module executing the mojo
Check JSON diffs carefully for trailing commas in hand edits
Pin the descriptor file in version control to avoid drift

When it happens

Trigger: Executing extension-descriptor with a configured extensionFile that does not exist, cannot be opened, or contains invalid JSON that Jackson cannot map to ObjectNode.

Common situations: Wrong relative/absolute path for extensionFile config; truncated or hand-broken extension.json (trailing commas, stray text); BOM/encoding issues; file deleted between configuration and execution in CI.

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

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/ae89534bbb17dfe5. Report an issue: GitHub.