What causes "Workflow can not be serialized to json" in conductor-oss/conductor?

Inspect the workflow's tasks and payloads for non-serializable or circular-reference values.

conductor-oss/conductor · error · TransientException

Workflow can not be serialized to json

Error message

Workflow can not be serialized to json

What it means

Thrown as a TransientException when objectMapper.writeValueAsString(workflow) raises a JsonProcessingException during removeWorkflowIndex while archiving a terminal workflow. The code writes the full workflow as RAW_JSON_FIELD plus an ARCHIVED_FIELD=true into the index before removing it from the DAO; if serialization fails the whole removal is aborted to avoid data loss (the DAO record is kept so it can be retried).

Source

Thrown at core/src/main/java/com/netflix/conductor/core/dal/ExecutionDAOFacade.java:371

     *
     * @param workflowId the id of the workflow to be removed
     * @param archiveWorkflow if true, the workflow and associated tasks will be archived in the
     *     {@link IndexDAO} before removal from {@link ExecutionDAO}.
     */
    public void removeWorkflow(String workflowId, boolean archiveWorkflow) {
        WorkflowModel workflow = getWorkflowModelFromDataStore(workflowId, true);

        // Index operations happen before DAO removal to prevent data loss on index failures.
        try {
            removeWorkflowIndex(workflow, archiveWorkflow);
        } catch (NotFoundException e) {
            if (archiveWorkflow) {
                throw e;
            }
            // Idempotent deletion: missing index records should not block DAO removal.
            LOGGER.info("Workflow {} not found in index during removal, continuing", workflowId, e);
        } catch (JsonProcessingException e) {
            throw new TransientException("Workflow can not be serialized to json", e);
        }

        // Task index removals run before DAO deletion for the same consistency guarantees.
        workflow.getTasks()
                .forEach(
                        task -> {
                            try {
                                removeTaskIndex(workflow, task, archiveWorkflow);
                            } catch (NotFoundException e) {
                                if (archiveWorkflow) {
                                    throw e;
                                }
                                // Idempotent deletion: missing index records should not block DAO
                                // removal.
                                LOGGER.info(
                                        "Task {} of workflow {} not found in index during removal, continuing",
                                        task.getTaskId(),
                                        workflowId,

View on GitHub (pinned to cf7c3e4a8a)

Solutions

Inspect the workflow's tasks and payloads for non-serializable or circular-reference values.
Ensure the ObjectMapper bean has all required Jackson modules registered (e.g. jdk8, JavaTime).
If you must remove the workflow despite serialization failure, call remove with archiveWorkflow=false so the index entry is deleted instead of archived.
Retry after fixing the payload; the DAO record is preserved, so nothing is lost.

Defensive patterns

Strategy: try-catch

Try / catch

try {
    executionDAOFacade.removeWorkflow(workflowId, /* archive */ true);
} catch (TransientException e) {
    // serialization failed during archival; DAO record preserved -> safe to retry after fix
}

Prevention

Ensure all task/workflow payloads are Jackson-serializable before they are stored.
If archival is optional, fall back to archive=false to delete from index instead.
Unit-test serialization of representative workflow graphs in your test harness.

When it happens

Trigger: Archiving (archiveWorkflow=true) a workflow whose model graph contains a value Jackson cannot serialize — e.g. a non-serializable task input/output, a self-referencing object, or a type without a matching Jackson serializer.

Common situations: A workflow task payload holds a custom Java type or an unserializable runtime object. A Jackson ObjectMapper configuration mismatch (missing modules) between the producing and archiving paths. Circular references in dynamic payload data.

Related errors

AI-assisted analysis of conductor-oss/conductor@cf7c3e4a8a (2026-08-14). Data as JSON: /api/errors/92a5c1ec72c60a90. Report an issue: GitHub.