What causes "Historic detail '" + detailId + "' does not have a variable value." in flowable/flowable-engine?

Treat this as 'value is null' rather than 'detail not found' — handle it as an empty value in the client

flowable/flowable-engine · warning · FlowableObjectNotFoundException

Historic detail '" + detailId + "' does not have a variable…

Error message

Historic detail '" + detailId + "' does not have a variable value.

What it means

A historic detail record was found but its associated variable value is null — the detail exists yet carries no variable payload (e.g. a variable was set to null at that point in history). Flowable throws FlowableObjectNotFoundException naming the detailId so clients know there is nothing to return.

Solutions

Treat this as 'value is null' rather than 'detail not found' — handle it as an empty value in the client
Avoid setting variables to null; remove them instead or use a sentinel value
Catch FlowableObjectNotFoundException and skip/represent null values in history views

Example fix

// before
runtimeService.setVariable(executionId, " approver", null)

// after
runtimeService.removeVariable(executionId, "approver") // or use a non-null sentinel

Defensive patterns

Strategy: fallback

Validate before calling

const detail = await getHistoricDetail(detailId);
if (detail.value == null || detail.value === undefined) {
  console.warn(`Detail ${detailId} has null variable value`);
}

Type guard

function hasValue(detail) { return detail != null && detail.value !== null && detail.value !== undefined; }

Try / catch

try { return await getVariable(detailId); } catch (e) { if (e.status === 404) return { value: null, detailId }; throw e; }

Prevention

Avoid setting variables to null in processes; remove them instead
Render null-valued history entries as empty in UIs
Check history data before linking detail ids into workflows

When it happens

Trigger: GET /history/historic-detail/{detailId} (via the variable/variable-data endpoints) where the HistoricVariableUpdate's value is null because the variable was assigned null in the process.

Common situations: Variables explicitly set to null during process execution; querying data for a detail created by a null assignment; race between deletion and query in some history levels.

Related errors

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/c025f221144bca16. Report an issue: GitHub.

Appendix: source

Thrown at modules/flowable-rest/src/main/java/org/flowable/rest/service/api/history/HistoricDetailDataResource.java:104

            throw new FlowableException("Unexpected exception getting variable data", ioe);
        }
    }

    public RestVariable getVariableFromRequest(boolean includeBinary, String detailId) {
        Object value = null;
        HistoricVariableUpdate variableUpdate = null;
        HistoricDetail detailObject = historyService.createHistoricDetailQuery().id(detailId).singleResult();
        if (detailObject instanceof HistoricVariableUpdate) {
            variableUpdate = (HistoricVariableUpdate) detailObject;
            value = variableUpdate.getValue();
        }
        
        if (restApiInterceptor != null) {
            restApiInterceptor.accessHistoryDetailById(detailObject);
        }

        if (value == null) {
            throw new FlowableObjectNotFoundException("Historic detail '" + detailId + "' does not have a variable value.", VariableInstanceEntity.class);
        } else {
            return restResponseFactory.createRestVariable(variableUpdate.getVariableName(), value, null, detailId, RestResponseFactory.VARIABLE_HISTORY_DETAIL, includeBinary);
        }
    }
}

View on GitHub (pinned to d6d39ce1c6)