flowable/flowable-engine · error · java.lang.IllegalArgumentException

businessCalendars can not be null

Error message

businessCalendars can not be null

What it means

Constructor validation in MapBusinessCalendarManager: the business calendar map passed in is null. The manager requires a (possibly empty) map to look up due-date calculators, and a null map would cause NPEs later during timer/job evaluation.

Solutions

1. Pass a non-null (possibly empty) map of business calendars
2. Use the no-arg constructor and register calendars afterwards

When it happens

Trigger: Thrown at modules/flowable-engine-common/src/main/java/org/flowable/common/engine/impl/calendar/MapBusinessCalendarManager.java:33 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/2f11e1e55e44d0fb. Report an issue: GitHub.

Appendix: source

Thrown at modules/flowable-engine-common/src/main/java/org/flowable/common/engine/impl/calendar/MapBusinessCalendarManager.java:33

import java.util.HashMap;
import java.util.Map;

import org.flowable.common.engine.api.FlowableException;

/**
 * @author Tom Baeyens
 */
public class MapBusinessCalendarManager implements BusinessCalendarManager {

    private final Map<String, BusinessCalendar> businessCalendars;

    public MapBusinessCalendarManager() {
        this.businessCalendars = new HashMap<>();
    }

    public MapBusinessCalendarManager(Map<String, BusinessCalendar> businessCalendars) {
        if (businessCalendars == null) {
            throw new IllegalArgumentException("businessCalendars can not be null");
        }

        this.businessCalendars = new HashMap<>(businessCalendars);
    }

    @Override
    public BusinessCalendar getBusinessCalendar(String businessCalendarRef) {
        BusinessCalendar businessCalendar = businessCalendars.get(businessCalendarRef);
        if (businessCalendar == null) {
            throw new FlowableException("Requested business calendar " + businessCalendarRef +
                    " does not exist. Allowed calendars are " + this.businessCalendars.keySet() + ".");
        }
        return businessCalendar;
    }

    public BusinessCalendarManager addBusinessCalendar(String businessCalendarRef, BusinessCalendar businessCalendar) {
        businessCalendars.put(businessCalendarRef, businessCalendar);
        return this;

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