flowable/flowable-engine · error · IOException

Error opening url:

Error message

Error opening url: 

What it means

When deploying processes found in an OSGi bundle, Extender.checkBundle opens a stream for each discovered URL and throws IOException('Error opening url: ...') if openStream() returns null. This means the resource URL exists syntactically but its contents cannot be read, so it cannot be added to the deployment builder.

Solutions

1. Verify the resource referenced by the URL actually exists inside the bundle (check Bundle-Wiring / Bundle content)
2. Confirm the bundle exports/includes the BPMN/BAR resources at the declared paths
3. Check any custom URL handlers (bar:, bpmn:) are functioning and returning valid connections
4. Log the failing URL and test opening it manually in the same container

Example fix

// before
URL url = new URL("bpmn:file:/missing/process.bpmn20.xml");
// after
URL url = new URL("bpmn:file:/processes/process.bpmn20.xml"); // ensure file exists in bundle
try (InputStream is = url.openStream()) {
    builder.addInputStream(getPath(url), is);
}

// before deploying from a bundle URL
URL url = ...;
URLConnection conn = url.openConnection();
long len = conn.getContentLengthLong();
if (len == 0) throw new IllegalStateException("Resource empty/unreadable: " + url);

try {
    deployFromBundle(bundle);
} catch (IOException e) {
    if (e.getMessage().startsWith("Error opening url")) {
        logger.error("Bundle resource unreadable: {} — check bundle contents and exports", e.getMessage(), e);
    }
    throw e;
}

When it happens

Trigger: url.openStream() returning null (or an URL handler returning a Connection whose stream is unavailable) for one of the BPMN/BAR resource URLs collected from a bundle during checkBundle.

Common situations: Resource pointed to by the URL was removed or not exported by the bundle; custom URL handlers failing silently; bundle resource paths declared in the manifest that don't match actual entries.

Understand the failure class

Background: "open() failed", "failed to open file", "cannot create file" — what a file open error means and how to fix it — this error's family across 42 libraries.

Related errors

• Bundle cannot be generated
• byte array for resource
• byte array for resource
• could not get byte array from resource
• could not get byte array from resource

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/80690b65983f6687. Report an issue: GitHub.

Appendix: source

Thrown at modules/flowable-osgi/src/main/java/org/flowable/osgi/Extender.java:221

                    }
                }
            }

            if (!pathList.isEmpty()) {
                LOGGER.debug("Found flowable process in bundle {} with paths: {}", bundle.getSymbolicName(), pathList);

                ProcessEngine engine = (ProcessEngine) engineServiceTracker.waitForService(timeout);
                if (engine == null) {
                    throw new IllegalStateException("Unable to find a ProcessEngine service");
                }

                RepositoryService service = engine.getRepositoryService();
                DeploymentBuilder builder = service.createDeployment();
                builder.name(bundle.getSymbolicName());
                for (URL url : pathList) {
                    InputStream is = url.openStream();
                    if (is == null) {
                        throw new IOException("Error opening url: " + url);
                    }
                    try {
                        builder.addInputStream(getPath(url), is);
                    } finally {
                        is.close();
                    }
                }
                builder.enableDuplicateFiltering();
                builder.deploy();
            } else {
                LOGGER.debug("No flowable process found in bundle {}", bundle.getSymbolicName());
            }
        } catch (Throwable t) {
            LOGGER.error("Unable to deploy flowable bundle", t);
        }
    }

    private void addEntry(Bundle bundle, String path, List<URL> pathList) {

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