flowable/flowable-engine · warning · FlowableException

byte array for resource

Error message

byte array for resource '${resourceName}' is null

What it means

After attempting to read the InputStream into a byte array, addInputStream checks whether the result is null and throws this error. IOUtils.toByteArray normally throws on failure rather than returning null, so this is a defensive guard against a null conversion result.

Solutions

1. Verify you are using the standard org.flowable version of EventDeploymentBuilderImpl and commons-io IOUtils; upgrade Flowable if a patched version fixes this path
2. Check the InputStream implementation for a toByteArray path that returns null and replace it with a plain stream (FileInputStream, ByteArrayInputStream)
3. Log stream contents/availability before the call to confirm bytes exist

Example fix

// before
deploymentBuilder.addInputStream(name, weirdStream); // custom stream returning null bytes
// after
deploymentBuilder.addInputStream(name, new FileInputStream(file)); // normal stream

byte[] check = IOUtils.toByteArray(inputStream);
if (check == null) throw new IllegalStateException("byte conversion produced null for " + resourceName);

try {
    deploymentBuilder.addInputStream(name, stream);
} catch (FlowableException e) {
    if (e.getMessage().contains("byte array for resource")) {
        // replace custom stream wrapper with a standard stream implementation
    } else { throw e; }
}

When it happens

Trigger: addInputStream where the byte conversion yields null (defensive path — practically only if IOUtils.toByteArray returns null, e.g. unusual IOUtil behavior or custom subclasses).

Common situations: Rare in practice; encountered when using custom IO utilities, exotic stream wrappers, or modified/copied code where the byte reading logic differs from stock Apache Commons IO behavior.

Understand the failure class

Background: "failed to read file", EACCES, ENOENT and "could not read <path>" errors: when a program can't read a file from disk — this error's family across 49 libraries.

Related errors

• could not get byte array from resource
• could not get byte array from resource
• Failed to read resource
• Failed to read resource
• problem reading zip input stream

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/b1796c2b0fb858fe. Report an issue: GitHub.

Appendix: source

Thrown at modules/flowable-event-registry/src/main/java/org/flowable/eventregistry/impl/repository/EventDeploymentBuilderImpl.java:65

        this.deployment = eventRegistryEngineConfiguration.getDeploymentEntityManager().create();
        this.resourceEntityManager = eventRegistryEngineConfiguration.getResourceEntityManager();
    }

    @Override
    public EventDeploymentBuilder addInputStream(String resourceName, InputStream inputStream) {
        if (inputStream == null) {
            throw new FlowableException("inputStream for resource '" + resourceName + "' is null");
        }

        byte[] bytes = null;
        try {
            bytes = IOUtils.toByteArray(inputStream);
        } catch (Exception e) {
            throw new FlowableException("could not get byte array from resource '" + resourceName + "'", e);
        }

        if (bytes == null) {
            throw new FlowableException("byte array for resource '" + resourceName + "' is null");
        }

        EventResourceEntity resource = resourceEntityManager.create();
        resource.setName(resourceName);
        resource.setBytes(bytes);
        deployment.addResource(resource);
        return this;
    }

    @Override
    public EventDeploymentBuilder addClasspathResource(String resource) {
        try (final InputStream inputStream = this.getClass().getClassLoader().getResourceAsStream(resource)) {
            if (inputStream == null) {
                throw new FlowableException("resource '" + resource + "' not found");
            }
            return addInputStream(resource, inputStream);
            
        } catch (IOException ex) {

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