CLIENT - unhandled error in GUI - ConcurrentModificationException
Nobody has claimed this yet.
- Dominant language
- Java
- Stars
- 2.4k
- Forks
- 940
- Avg merge
- 2d 12h
- Merged PRs (30d)
- 160
Description
Error type: CLIENT - unhandled error in GUI - ConcurrentModificationException
Client version: 1.4.57-V2 (build: 2025-07-25 13:53)
Java version: 1.8.0_202
Default charset: UTF-8
ConcurrentModificationException - look at server or client logs for more details
Stack trace:
java.util.ArrayList$Itr.checkForComodification(Unknown Source)
java.util.ArrayList$Itr.next(Unknown Source)
org.mage.plugins.card.CardPluginImpl.sortPermanents(CardPluginImpl.java:356)
mage.client.plugins.impl.Plugins.sortPermanents(Plugins.java:137)
mage.client.util.layout.impl.CardLayoutStrategyImpl.doLayout(CardLayoutStrategyImpl.java:60)
mage.client.game.BattlefieldPanel.sortLayout(BattlefieldPanel.java:273)
mage.client.game.BattlefieldPanel.update(BattlefieldPanel.java:264)
mage.client.game.PlayAreaPanel.update(PlayAreaPanel.java:515)
mage.client.game.GamePanel.lambda$reloadThemeRelatedGraphic$5(GamePanel.java:661)
java.util.ArrayList.forEach(Unknown Source)
and other 8 lines
Contributor guide
No contributing guide indexed for this repository
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with the reported stack-trace locations in org/mage/plugins/card/CardPluginImpl.java, mage/client/plugins/impl/Plugins.java, and mage/client/util/layout/impl/CardLayoutStrategyImpl.java. Trace the BattlefieldPanel update and theme-reload path, then reproduce the GUI error using the reported client version. Done means this ConcurrentModificationException no longer appears during the affected update and layout flow.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- java
- Domain
- desktop, game-dev
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 35/100