flowable/flowable-engine · error · FlowableException

HTTP method not supported

Error message

${method} HTTP method not supported

What it means

prepareRequest builds the Apache HttpRequest via a switch on the HTTP method. Only GET, POST, PUT, DELETE, PATCH, HEAD, OPTIONS (per the switch) are supported; any other method string reaches the default branch and throws FlowableException with '<method> HTTP method not supported'. The delegating layer normally restricts methods, but the expression-driven method value can still resolve to something unsupported.

Solutions

1. Change the requestMethod to one of the supported verbs (GET, POST, PUT, DELETE, PATCH, HEAD, OPTIONS)
2. If the target API only supports the non-standard verb, use a supported verb with an override header (e.g. X-HTTP-Method-Override) if the server honors it
3. Validate/sanitize the variable feeding requestMethod before the task
4. Extend the client via a custom HttpRequestInformation handler if non-standard methods are truly required

Example fix

// before
execution.setVariable("httpMethod", "PURGE");
// after
execution.setVariable("httpMethod", "POST");

java.util.Set<String> SUPPORTED = java.util.Set.of("GET","POST","PUT","DELETE","PATCH","HEAD","OPTIONS");
String m = (String) execution.getVariable("httpMethod");
if (m == null || !SUPPORTED.contains(m.trim().toUpperCase())) {
    throw new IllegalArgumentException("Unsupported HTTP method: " + m);
}

boolean isSupportedMethod(String m) { return m != null && java.util.Set.of("GET","POST","PUT","DELETE","PATCH","HEAD","OPTIONS").contains(m.trim().toUpperCase()); }

try {
    client.prepareRequest(requestInfo);
} catch (FlowableException e) {
    if (e.getMessage() != null && e.getMessage().endsWith("HTTP method not supported")) {
        // reject or substitute a supported verb
    } else { throw e; }
}

When it happens

Trigger: The HTTP task's requestMethod expression resolves at runtime to a method outside the supported set (e.g. 'TRACE', 'CONNECT', lowercase handled, but a custom/invalid value like 'PURGE' or 'GET2'), reaching prepareRequest directly.

Common situations: Passing the HTTP method from a process variable that came from user input or an external system; typos like 'DELET'; supporting non-standard verbs used by some APIs (e.g. Elasticsearch PURGE) through generic HTTP tasks.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

• can't clear configuration beans
• can't search values in configuration beans
• Cannot change fixed value with
• Cannot move a history job to an executable job
• CommandInvoker must be the last interceptor in the chain

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/66e4733dc485aad0. Report an issue: GitHub.

Appendix: source

Thrown at modules/flowable-http-common/src/main/java/org/flowable/http/common/impl/apache/ApacheHttpComponentsFlowableHttpClient.java:223

                    setRequestEntity(requestInfo, patch);
                    request = patch;
                    break;
                }
                case "DELETE": {
                    HttpDeleteWithBody delete = new HttpDeleteWithBody(uri);
                    setRequestEntity(requestInfo, delete);
                    request = delete;
                    break;
                }
                case "HEAD": {
                    request = new HttpHead(uri);
                    break;
                }
                case "OPTIONS":
                    request = new HttpOptions(uri);
                    break;
                default: {
                    throw new FlowableException(requestInfo.getMethod() + " HTTP method not supported");
                }
            }

            setHeaders(request, requestInfo.getHttpHeaders());
            setHeaders(request, requestInfo.getSecureHttpHeaders());

            setConfig(request, requestInfo);
            return new ApacheHttpComponentsExecutableHttpRequest(request);
        } catch (URISyntaxException ex) {
            throw new FlowableException("Invalid URL exception occurred", ex);
        } catch (IOException ex) {
            throw new FlowableException("IO exception occurred", ex);
        }
    }

    protected URI createUri(String url) throws URISyntaxException {
        String uri = SPACE_CHARACTER_PATTERN.matcher(url).replaceAll(ENCODED_SPACE_CHARACTER);
        return new URI(PLUS_CHARACTER_PATTERN.matcher(uri).replaceAll(ENCODED_PLUS_CHARACTER));

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