Index: src/org/openstreetmap/josm/io/OsmServerWriter.java
===================================================================
--- src/org/openstreetmap/josm/io/OsmServerWriter.java	(revision 19123)
+++ src/org/openstreetmap/josm/io/OsmServerWriter.java	(working copy)
@@ -5,6 +5,7 @@
 import static org.openstreetmap.josm.tools.I18n.tr;
 import static org.openstreetmap.josm.tools.I18n.trn;
 
+import java.time.Instant;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Iterator;
@@ -18,6 +19,7 @@
 import org.openstreetmap.josm.data.osm.OsmPrimitiveType;
 import org.openstreetmap.josm.gui.progress.NullProgressMonitor;
 import org.openstreetmap.josm.gui.progress.ProgressMonitor;
+import org.openstreetmap.josm.io.ChangesetClosedException.Source;
 import org.openstreetmap.josm.tools.CheckParameterUtil;
 
 /**
@@ -172,6 +174,11 @@
                                 "({0}/{1}) Uploading {2} objects...",
                                 chunk.size(), i, numChunks, chunk.size()));
                 processed.addAll(api.uploadDiff(chunk, progressMonitor.createSubTaskMonitor(ProgressMonitor.ALL_TICKS, false)));
+                // see #23738: server will close CS if maximum changeset size was reached
+                if (processed.size() >= api.getCapabilities().getMaxChangesetSize()) {
+                    throw new ChangesetClosedException(api.getChangeset().getId(), Instant.now(), Source.UPLOAD_DATA);
+                }
+
             }
         } finally {
             progressMonitor.finishTask();