flowable/flowable-engine · error · FlowableIllegalArgumentException

Illegal action: '" + request.getAction() + "'.

Error message

Illegal action: '" + request.getAction() + "'.

What it means

Bulk deletion of historic process instances accepts an action envelope; only the action string "delete" (BulkDeleteInstancesRestActionRequest.DELETE_ACTION) is valid. Any other action value causes FlowableIllegalArgumentException listing the received action.

Source

Thrown at modules/flowable-rest/src/main/java/org/flowable/rest/service/api/history/HistoricProcessInstanceCollectionResource.java:315

    }

    @ApiOperation(value = "Post action request to delete a bulk of historic process instances", tags = {
            "Manage History Process Instances" }, nickname = "bulkDeleteHistoricProcessInstances", code = 204)
    @ApiResponses(value = {
            @ApiResponse(code = 204, message = "Indicates the bulk of historic process instances was found and deleted. Response body is left empty intentionally."),
            @ApiResponse(code = 404, message = "Indicates at least one requested process instance was not found.")
    })
    @PostMapping(value = "/history/historic-process-instances/delete")
    @ResponseStatus(value = HttpStatus.NO_CONTENT)
    public void bulkDeleteHistoricProcessInstances(@ApiParam(name = "bulkDeleteRestActionRequest")
    @RequestBody BulkDeleteInstancesRestActionRequest request) {
        if (BulkDeleteInstancesRestActionRequest.DELETE_ACTION.equals(request.getAction())) {
            if (restApiInterceptor != null) {
                restApiInterceptor.bulkDeleteHistoricProcessInstances(request.getInstanceIds());
            }
            historyService.bulkDeleteHistoricProcessInstances(request.getInstanceIds());
        } else {
            throw new FlowableIllegalArgumentException("Illegal action: '" + request.getAction() + "'.");
        }
    }
}

View on GitHub (pinned to d6d39ce1c6)

Solutions

1. Set the request body action to "delete" exactly
2. Ensure the action field is present and non-null in the JSON payload
3. Confirm instanceIds are also provided since the interceptor and historyService require them

Example fix

// before
{"action":"remove","instanceIds":["p1","p2"]}
// after
{"action":"delete","instanceIds":["p1","p2"]}

if (req.action !== 'delete') throw new Error('bulk action must be "delete"');

const isDeleteAction = (a) => a === 'delete';

catch (e) { if (e.response && e.response.status === 400 && /Illegal action/.test(e.response.data.message)) { /* correct action field and retry */ } throw e; }

When it happens

Trigger: POST to the historic process instance bulk-delete collection endpoint with a body whose action field is not exactly "delete" (null, typo, different verb).

Common situations: Generic delete UIs sending action names like "remove" or "purge"; null action omitted from the JSON body; API drift after upgrading Flowable REST versions.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

• Illegal action: '${request.getAction()}'.
• Unsupported variable query operation: " + variable.getVariab
• Illegal action: '${action}'.
• Variable operation is missing for variable: ${variable.getNa
• Variable value is missing for variable: ${variable.getName()

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/fcfcfa2ed80d3497. Report an issue: GitHub.