Index: trunk/src/org/openstreetmap/josm/gui/layer/AbstractTileSourceLayer.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/layer/AbstractTileSourceLayer.java	(revision 9718)
+++ trunk/src/org/openstreetmap/josm/gui/layer/AbstractTileSourceLayer.java	(revision 9719)
@@ -1690,5 +1690,4 @@
                         TMSCachedTileLoader.getNewThreadPoolExecutor("Precache downloader"));
             }
-
         }
 
@@ -1718,8 +1717,10 @@
         @Override
         public void tileLoadingFinished(Tile tile, boolean success) {
+            int processed = this.processedCount.incrementAndGet();
             if (success) {
-                int processed = this.processedCount.incrementAndGet();
                 this.progressMonitor.worked(1);
                 this.progressMonitor.setCustomText(tr("Downloaded {0}/{1} tiles", processed, totalCount));
+            } else {
+                Main.warn("Tile loading failure: " + tile + " - " + tile.getErrorMessage());
             }
         }
Index: trunk/src/org/openstreetmap/josm/gui/layer/gpx/DownloadWmsAlongTrackAction.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/layer/gpx/DownloadWmsAlongTrackAction.java	(revision 9718)
+++ trunk/src/org/openstreetmap/josm/gui/layer/gpx/DownloadWmsAlongTrackAction.java	(revision 9719)
@@ -36,6 +36,6 @@
 
 /**
- * Class downloading WMS and TMS along the GPX track
- *
+ * Class downloading WMS and TMS along the GPX track.
+ * @since 5715
  */
 public class DownloadWmsAlongTrackAction extends AbstractAction {
@@ -51,7 +51,49 @@
     }
 
-    @Override
-    public void actionPerformed(ActionEvent e) {
-        final List<LatLon> points = new ArrayList<>();
+    static class PrecacheWmsTask extends PleaseWaitRunnable {
+
+        private final AbstractTileSourceLayer layer;
+        private final List<LatLon> points;
+        private PrecacheTask precacheTask;
+
+        protected PrecacheWmsTask(AbstractTileSourceLayer layer, List<LatLon> points) {
+            super(tr("Precaching WMS"));
+            this.layer = layer;
+            this.points = points;
+        }
+
+        @Override
+        protected void realRun() throws SAXException, IOException, OsmTransferException {
+            precacheTask = layer.new PrecacheTask(progressMonitor);
+            layer.downloadAreaToCache(precacheTask, points, 0, 0);
+            while (!precacheTask.isFinished() && !progressMonitor.isCanceled()) {
+                synchronized (this) {
+                    try {
+                        wait(200);
+                    } catch (InterruptedException ex) {
+                        Main.warn("InterruptedException in "+getClass().getSimpleName()+" while precaching WMS");
+                    }
+                }
+            }
+        }
+
+        @Override
+        protected void finish() {
+            // Do nothing
+        }
+
+        @Override
+        protected void cancel() {
+            precacheTask.cancel();
+        }
+
+        @Override
+        public ProgressTaskId canRunInBackground() {
+            return ProgressTaskIds.PRECACHE_WMS;
+        }
+    }
+
+    PrecacheWmsTask createTask() {
+        List<LatLon> points = new ArrayList<>();
         for (GpxTrack trk : data.tracks) {
             for (GpxTrackSegment segment : trk.getSegments()) {
@@ -64,38 +106,12 @@
             points.add(p.getCoor());
         }
-        final AbstractTileSourceLayer layer = askedLayer();
-        if (layer != null) {
-            PleaseWaitRunnable task = new PleaseWaitRunnable(tr("Precaching WMS")) {
-                private PrecacheTask precacheTask;
+        AbstractTileSourceLayer layer = askedLayer();
+        return layer != null ? new PrecacheWmsTask(layer, points) : null;
+    }
 
-                @Override
-                protected void realRun() throws SAXException, IOException, OsmTransferException {
-                    precacheTask = layer.new PrecacheTask(progressMonitor);
-                    layer.downloadAreaToCache(precacheTask, points, 0, 0);
-                    while (!precacheTask.isFinished() && !progressMonitor.isCanceled()) {
-                        synchronized (this) {
-                            try {
-                                wait(200);
-                            } catch (InterruptedException ex) {
-                                Main.warn("InterruptedException in "+getClass().getSimpleName()+" while precaching WMS");
-                            }
-                        }
-                    }
-                }
-
-                @Override
-                protected void finish() {
-                }
-
-                @Override
-                protected void cancel() {
-                    precacheTask.cancel();
-                }
-
-                @Override
-                public ProgressTaskId canRunInBackground() {
-                    return ProgressTaskIds.PRECACHE_WMS;
-                }
-            };
+    @Override
+    public void actionPerformed(ActionEvent e) {
+        PrecacheWmsTask task = createTask();
+        if (task != null) {
             Main.worker.execute(task);
         }
@@ -103,4 +119,7 @@
 
     protected AbstractTileSourceLayer askedLayer() {
+        if (!Main.isDisplayingMapView()) {
+            return null;
+        }
         List<AbstractTileSourceLayer> targetLayers = Main.map.mapView.getLayersOfType(AbstractTileSourceLayer.class);
         if (targetLayers.isEmpty()) {
Index: trunk/test/data/minimal.gpx
===================================================================
--- trunk/test/data/minimal.gpx	(revision 9719)
+++ trunk/test/data/minimal.gpx	(revision 9719)
@@ -0,0 +1,49 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no" ?>
+<gpx xmlns="http://www.topografix.com/GPX/1/1" creator="MapSource 6.16.3" version="1.1" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.topografix.com/GPX/1/1 http://www.topografix.com/GPX/1/1/gpx.xsd">
+
+  <metadata>
+    <link href="http://www.garmin.com">
+      <text>Garmin International</text>
+    </link>
+    <time>2016-01-09T19:37:38Z</time>
+    <bounds maxlat="47.201499743387103" maxlon="8.798418799415231" minlat="47.18490038998425" minlon="8.77192972227931"/>
+  </metadata>
+
+  <wpt lat="47.192017380148172" lon="8.795854020863771">
+    <ele>480</ele>
+    <time>2016-01-09T19:29:38Z</time>
+    <name>Schranke</name>
+    <cmt>Pfad</cmt>
+    <desc>Pfad</desc>
+    <sym>Toll Booth</sym>
+    <extensions>
+      <gpxx:WaypointExtension xmlns:gpxx="http://www.garmin.com/xmlschemas/GpxExtensions/v3">
+        <gpxx:DisplayMode>SymbolAndName</gpxx:DisplayMode>
+      </gpxx:WaypointExtension>
+    </extensions>
+  </wpt>
+
+  <trk>
+    <name>2016-01-03 20:40:14</name>
+    <extensions>
+      <gpxx:TrackExtension xmlns:gpxx="http://www.garmin.com/xmlschemas/GpxExtensions/v3">
+        <gpxx:DisplayColor>Black</gpxx:DisplayColor>
+      </gpxx:TrackExtension>
+    </extensions>
+    <trkseg>
+      <trkpt lat="47.19286847859621" lon="8.79732714034617">
+        <ele>471.86000000000001</ele>
+        <time>2016-01-03T11:59:58Z</time>
+      </trkpt>
+      <trkpt lat="47.192921955138445" lon="8.797342479228973">
+        <ele>471.43000000000001</ele>
+        <time>2016-01-03T11:59:59Z</time>
+      </trkpt>
+      <trkpt lat="47.192975012585521" lon="8.797344239428639">
+        <ele>470.69</ele>
+        <time>2016-01-03T12:00:00Z</time>
+      </trkpt>
+    </trkseg>
+  </trk>
+
+</gpx>
Index: trunk/test/unit/org/openstreetmap/josm/gui/layer/gpx/DownloadWmsAlongTrackActionTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/gui/layer/gpx/DownloadWmsAlongTrackActionTest.java	(revision 9719)
+++ trunk/test/unit/org/openstreetmap/josm/gui/layer/gpx/DownloadWmsAlongTrackActionTest.java	(revision 9719)
@@ -0,0 +1,65 @@
+// License: GPL. For details, see LICENSE file.
+package org.openstreetmap.josm.gui.layer.gpx;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.openstreetmap.josm.JOSMFixture;
+import org.openstreetmap.josm.Main;
+import org.openstreetmap.josm.TestUtils;
+import org.openstreetmap.josm.data.gpx.GpxData;
+import org.openstreetmap.josm.data.imagery.ImageryInfo;
+import org.openstreetmap.josm.gui.layer.TMSLayer;
+import org.openstreetmap.josm.gui.layer.gpx.DownloadWmsAlongTrackAction.PrecacheWmsTask;
+import org.openstreetmap.josm.io.GpxReaderTest;
+
+/**
+ * Unit tests of {@link DownloadWmsAlongTrackAction} class.
+ */
+public class DownloadWmsAlongTrackActionTest {
+
+    /**
+     * Setup test.
+     */
+    @BeforeClass
+    public static void setUpBeforeClass() {
+        JOSMFixture.createUnitTestFixture().init(true);
+    }
+
+    /**
+     * Test action without layer.
+     */
+    @Test
+    public void testNoLayer() {
+        assertNull(new DownloadWmsAlongTrackAction(new GpxData()).createTask());
+    }
+
+    /**
+     * Test action with a TMS layer.
+     * @throws Exception if an error occurs
+     */
+    @Test
+    public void testTmsLayer() throws Exception {
+        // Create new TMS layer and clear cache
+        TMSLayer layer = new TMSLayer(new ImageryInfo("OSM TMS", "https://a.tile.openstreetmap.org/{zoom}/{x}/{y}.png", "tms", null, null));
+        try {
+            Main.main.addLayer(layer);
+            TMSLayer.getCache().clear();
+            assertTrue(TMSLayer.getCache().getMatching(".*").isEmpty());
+            // Perform action
+            final GpxData gpx = GpxReaderTest.parseGpxData(TestUtils.getTestDataRoot() + "minimal.gpx");
+            PrecacheWmsTask task = new DownloadWmsAlongTrackAction(gpx).createTask();
+            assertNotNull(task);
+            task.run();
+            // Ensure cache is not empty
+            assertFalse(TMSLayer.getCache().getMatching(".*").isEmpty());
+        } finally {
+            // Ensure we clean the place before leaving, even if test fails.
+            Main.main.removeLayer(layer);
+        }
+    }
+}