quarkusio/quarkus · error · MojoExecutionException

Unable to write quarkus native image agent caller filter to

Error message

Unable to write quarkus native image agent caller filter to <path>

What it means

GenerateCodeTestsMojo.generateNativeAgentFilter writes a JSON caller-filter file used by the Quarkus native image agent. If BufferedWriter/appendTo throws IOException it wraps it in this MojoExecutionException naming the target path. The failure is purely about persisting the generated filter file to disk.

Source

Thrown at devtools/maven/src/main/java/io/quarkus/maven/GenerateCodeTestsMojo.java:104

    }

    private void generateNativeAgentFilter(Collection<String> packageNames, Path path) throws MojoExecutionException {
        final Json.JsonObjectBuilder result = Json.object();

        final Json.JsonArrayBuilder rules = Json.array();
        packageNames.stream()
                .map(packageName -> Json.object().put("excludeClasses", packageName + ".**"))
                .forEach(rules::add);
        result.put("rules", rules);

        final Json.JsonArrayBuilder regexRules = Json.array();
        regexRules.add(Json.object().put("excludeClasses", ".*_Bean"));
        result.put("regexRules", regexRules);

        try (BufferedWriter writer = new BufferedWriter(new FileWriter(path.toFile(), StandardCharsets.UTF_8))) {
            result.appendTo(writer);
        } catch (IOException e) {
            throw new MojoExecutionException("Unable to write quarkus native image agent caller filter to " + path, e);
        }
    }

    private Collection<ResolvedDependency> getDependencies() throws MojoExecutionException {
        try (CuratedApplication curatedApplication = bootstrapApplication(LaunchMode.TEST)) {
            return curatedApplication.getApplicationModel().getDependencies();
        } catch (Exception any) {
            throw new MojoExecutionException("Quarkus native image agent filter generation phase has failed", any);
        }
    }

    private Set<String> getCommonExcludePackageNames() {
        Set<String> packageNames = new HashSet<>();
        // Any calls that access or originate in these packages
        // that require native configuration should be handled by Quarkus.
        packageNames.add("io.netty");
        packageNames.add("io.quarkus");
        packageNames.add("io.smallrye");

View on GitHub (pinned to e1c734241f)

Solutions

1. Ensure the parent directory of the filter file exists and is writable (e.g. `mvn quarkus:generate-code-tests` after a build creates target/)
2. Check file permissions on the output path and that it is not a directory
3. Free disk space / verify the path configured for the agent filter files is valid

Example fix

// before
mkdir target  # only if missing, before running
mvn quarkus:generate-code-tests
// after
mvn process-test-classes quarkus:generate-code-tests  # ensures target/ exists

test -w <filter-file-dir> && test ! -d <filter-file> && df -h <filter-file-dir>

try {
    mvn quarkus:generate-code-tests
} catch (MojoExecutionException e) {
    // check the path named in the message: create parent dir / fix permissions
}

When it happens

Trigger: Opening or writing path.toFile() with FileWriter(UTF-8) fails — e.g. the target directory does not exist, the path is a directory, or the process lacks write permission.

Common situations: target/ directory removed or read-only during CI; running `mvn quarkus:generate-code-tests` with -Dquarkus.test.native-image-agent-filter-files pointing to an unwritable/nonexistent location; disk-full conditions.

Understand the failure class

Background: "Permission denied" / "Failed to write" file errors: why a library can't write its files to disk (EACCES, EPERM, ENOSPC) and how to fix them — this error's family across 43 libraries.

Related errors

• Failed to initialize file output writer
• Failed to log the dependency list to a file
• Failed to initialize file output writer
• Failed to log the dependency tree to a file
• Failed to transform native image agent configuration

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/133e7c9e16b46742. Report an issue: GitHub.