Index: src/org/openstreetmap/josm/plugins/PluginListParser.java
===================================================================
--- src/org/openstreetmap/josm/plugins/PluginListParser.java	(revision 16850)
+++ src/org/openstreetmap/josm/plugins/PluginListParser.java	(working copy)
@@ -94,7 +94,7 @@
         try {
             if (name != null) {
                 PluginInformation info = createInfo(name, url, manifest);
-                for (PluginProxy plugin : PluginHandler.pluginList) {
+                for (PluginProxy plugin : new LinkedList<>(PluginHandler.pluginList)) {
                     if (plugin.getPluginInformation().name.equals(info.getName())) {
                         info.localversion = plugin.getPluginInformation().localversion;
                     }