What causes "couldn't read input stream ${inputStreamName}" in flowable/flowable-engine?

Check the wrapped cause (e.getCause()) to identify the underlying I/O failure.

flowable/flowable-engine · error · org.activiti.engine.ActivitiException

couldn't read input stream

Error message

couldn't read input stream ${inputStreamName}

What it means

IoUtil.readInputStream copies an InputStream into a byte[]; any exception during reading/writing (IOException, closed stream, broken connection) is wrapped in this ActivitiException, with the stream's descriptive name included.

Solutions

Check the wrapped cause (e.getCause()) to identify the underlying I/O failure.
Ensure the InputStream is open and not yet fully consumed when passed in.
Use standard java.io/nio APIs with try-with-resources for custom scenarios instead of re-reading the same stream.

Example fix

// before
byte[] data = IoUtil.readInputStream(inputStream, "resource");
byte[] again = IoUtil.readInputStream(inputStream, "resource"); // throws: stream consumed
// after
byte[] data = IoUtil.readInputStream(inputStream, "resource");
byte[] again = data; // reuse bytes; never re-read a consumed stream

Defensive patterns

Strategy: try-catch

Try / catch

try {
    byte[] data = IoUtil.readInputStream(in, name);
} catch (ActivitiException e) {
    if (e.getCause() instanceof java.io.IOException) { /* reopen stream or abort */ }
}

Prevention

Never read the same InputStream twice; streams are single-use
Use try-with-resources and check stream open state before passing it
For remote streams, apply timeouts and retry with a fresh stream

When it happens

Trigger: Calling IoUtil.readInputStream(inputStream, name) where the stream throws during read(): stream already closed, socket broken mid-read, or errors from a file/network-backed stream.

Common situations: Reading deployment resources from a closed connection; streams consumed twice (second read after the stream is exhausted); timeouts on remote resource streams.

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

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/0040f9bf2acbfd7e. Report an issue: GitHub.

Appendix: source

Thrown at modules/flowable5-engine/src/main/java/org/activiti/engine/impl/util/IoUtil.java:45

/**
 * @author Tom Baeyens
 * @author Frederik Heremans
 * @author Joram Barrez
 */
public class IoUtil {

    public static byte[] readInputStream(InputStream inputStream, String inputStreamName) {
        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        byte[] buffer = new byte[16 * 1024];
        try {
            int bytesRead = inputStream.read(buffer);
            while (bytesRead != -1) {
                outputStream.write(buffer, 0, bytesRead);
                bytesRead = inputStream.read(buffer);
            }
        } catch (Exception e) {
            throw new ActivitiException("couldn't read input stream " + inputStreamName, e);
        }
        return outputStream.toByteArray();
    }

    public static String readFileAsString(String filePath) {
        byte[] buffer = new byte[(int) getFile(filePath).length()];
        BufferedInputStream inputStream = null;
        try {
            inputStream = new BufferedInputStream(new FileInputStream(getFile(filePath)));
            inputStream.read(buffer);
        } catch (Exception e) {
            throw new ActivitiException("Couldn't read file " + filePath + ": " + e.getMessage());
        } finally {
            IoUtil.closeSilently(inputStream);
        }
        return new String(buffer);
    }

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