ISSUE

A poll timer error randomly displayed when a robot was ran.

CAUSE

Defect 1029291.

SOLUTION

This is a programming error and can be triggered by race conditions when evaluating a guard in the robot. When this occurs, a robot's guard might yield an unexpected result, causing the robot to fail or continue processing after logging the error. A reproduction scenario has not yet been identified.

Full text of error stack:

kapow.robot.common.task.RoboServerApplicationStartupTasks - Uncaught exception in Thread[GuardManager poll timer,5,main].

java.util.ConcurrentModificationExcepton: null

at java.util.HashMap$HashIterator.nextNode(Unknown Source) ~[?:?]

at java.util.HashMap$KeyIterator.next(Unknown Source) ~[?:?]

at com.kapowtech.hub.event.ApplicationGuardManager.checkGuards(ApplicationGuardManager.java:100) ~[kapowhub-client-11_5-2628.jar:?]

at com.kapowtech.hub.event.ApplicationGuardManager.checkGuardsOnPoll(ApplicationGuardManager.java:90) ~[kapowhub-client-11_5-2628.jar:?]

at com.kapowtech.hub.event.HubGuardManager.tick(HubGuardManager.java:99) ~[kapowhub-client-11_5-2628.jar:?]

at com.kapowtech.hub.event.HubGuardManager$1.run(HubGuardManager.java:85) ~[kapowhub-client-11_5-2628.jar:?]

at java.util.TimerThread.mainLoop(Unknown Source) ~[?:?]

at java.util.TimerThread.run(Unknown Source) ~[?:?]

2026-07-02 10:12:39,534 ERROR kapow.servermessagelog - Thread[GuardManager poll timer,5,main]  ̗ O  ߑ  ܂  Bnull java.util.ConcurrentModificationException

at java.base/java.util.HashMap$HashIterator.nextNode(Unknown Source)

at java.base/java.util.HashMap$KeyIterator.next(Unknown Source)

at com.kapowtech.hub.event.ApplicationGuardManager.checkGuards(ApplicationGuardManager.java:100)

at com.kapowtech.hub.event.ApplicationGuardManager.checkGuardsOnPoll(ApplicationGuardManager.java:90)

at com.kapowtech.hub.event.HubGuardManager.tick(HubGuardManager.java:99)

at com.kapowtech.hub.event.HubGuardManager$1.run(HubGuardManager.java:85)

at java.base/java.util.TimerThread.mainLoop(Unknown Source)

at java.base/java.util.TimerThread.run(Unknown Source)