diff --git a/main/src/com/google/refine/operations/column/ColumnAdditionByFetchingURLsOperation.java b/main/src/com/google/refine/operations/column/ColumnAdditionByFetchingURLsOperation.java
index 0029baa9a..32d4188f4 100644
--- a/main/src/com/google/refine/operations/column/ColumnAdditionByFetchingURLsOperation.java
+++ b/main/src/com/google/refine/operations/column/ColumnAdditionByFetchingURLsOperation.java
@@ -148,14 +148,6 @@ public class ColumnAdditionByFetchingURLsOperation extends EngineDependentOperat
     
     @Override
     public Process createProcess(Project project, Properties options) throws Exception {
-        Column column = project.columnModel.getColumnByName(_baseColumnName);
-        if (column == null) {
-            throw new Exception("No column named " + _baseColumnName);
-        }
-        if (project.columnModel.getColumnByName(_newColumnName) != null) {
-            throw new Exception("Another column already named " + _newColumnName);
-        }
-        
         Engine engine = createEngine(project);
         engine.initializeFromJSON(_engineConfig);
         
@@ -209,6 +201,16 @@ public class ColumnAdditionByFetchingURLsOperation extends EngineDependentOperat
         
         @Override
         public void run() {
+            Column column = _project.columnModel.getColumnByName(_baseColumnName);
+            if (column == null) {
+                _project.processManager.onFailedProcess(this, new Exception("No column named " + _baseColumnName));
+                return;
+            }
+            if (_project.columnModel.getColumnByName(_newColumnName) != null) {
+                _project.processManager.onFailedProcess(this, new Exception("Another column already named " + _newColumnName));
+                return;
+            }
+            
             List<CellAtRow> urls = new ArrayList<CellAtRow>(_project.rows.size());
             
             FilteredRows filteredRows = _engine.getAllFilteredRows();
diff --git a/main/src/com/google/refine/process/ProcessManager.java b/main/src/com/google/refine/process/ProcessManager.java
index bbc11328d..2abb37c84 100644
--- a/main/src/com/google/refine/process/ProcessManager.java
+++ b/main/src/com/google/refine/process/ProcessManager.java
@@ -46,6 +46,7 @@ import com.google.refine.history.HistoryProcess;
 
 public class ProcessManager implements Jsonizable {
     protected List<Process> _processes = new LinkedList<Process>();
+    protected List<Exception> _latestExceptions = null;
     
     public ProcessManager() {
         
@@ -62,11 +63,22 @@ public class ProcessManager implements Jsonizable {
         }
         writer.endArray();
         
+        if (_latestExceptions != null) {
+            writer.key("exceptions"); writer.array();
+            for (Exception e : _latestExceptions) {
+                writer.object();
+                writer.key("message"); writer.value(e.getLocalizedMessage());
+                writer.endObject();
+            }
+            writer.endArray();
+        }
+        
         writer.endObject();
     }
 
     public HistoryEntry queueProcess(Process process) throws Exception {
         if (process.isImmediate() && _processes.size() == 0) {
+            _latestExceptions = null;
             return process.performImmediate();
         } else {
             _processes.add(process);
@@ -78,6 +90,7 @@ public class ProcessManager implements Jsonizable {
     
     public boolean queueProcess(HistoryProcess process) throws Exception {
         if (process.isImmediate() && _processes.size() == 0) {
+            _latestExceptions = null;
             return process.performImmediate() != null;
         } else {
             _processes.add(process);
@@ -96,6 +109,18 @@ public class ProcessManager implements Jsonizable {
         update();
     }
     
+    public void onFailedProcess(Process p, Exception exception) {
+        List<Exception> exceptions = new LinkedList<Exception>();
+        exceptions.add(exception);
+        onFailedProcess(p, exceptions);
+    }
+    
+    public void onFailedProcess(Process p, List<Exception> exceptions) {
+        _latestExceptions = exceptions;
+        _processes.remove(p);
+        // Do not call update(); Just pause?
+    }
+    
     public void cancelAll() {
         for (Process p : _processes) {
             if (!p.isImmediate() && p.isRunning()) {
@@ -103,12 +128,14 @@ public class ProcessManager implements Jsonizable {
             }
         }
         _processes.clear();
+        _latestExceptions = null;
     }
     
     protected void update() {
         while (_processes.size() > 0) {
             Process p = _processes.get(0);
             if (p.isImmediate()) {
+                _latestExceptions = null;
                 try {
                     p.performImmediate();
                 } catch (Exception e) {
@@ -120,6 +147,7 @@ public class ProcessManager implements Jsonizable {
                 _processes.remove(0);
             } else {
                 if (!p.isRunning()) {
+                    _latestExceptions = null;
                     p.startPerforming(this);
                 }
                 break;
diff --git a/main/webapp/modules/core/scripts/project/process-panel.js b/main/webapp/modules/core/scripts/project/process-panel.js
index 0109442c1..b4a4bed50 100644
--- a/main/webapp/modules/core/scripts/project/process-panel.js
+++ b/main/webapp/modules/core/scripts/project/process-panel.js
@@ -191,6 +191,28 @@ ProcessPanel.prototype._render = function(newData) {
   }
   this._data = newData;
 
+  if (this._data.exceptions) {
+    var messages = $.map(this._data.exceptions, function(e) {
+      return e.message;
+    }).join('\n');
+    
+    if (this._data.processes.length == 0) {
+      window.alert('The last operation encountered some errors:\n' + messages);
+    } else {
+      if (window.confirm('The last operation encountered some errors:\n' + messages +
+            '\n\nContinue with the remaining operations?')) {
+        $.post(
+          "/command/core/apply-operations?" + $.param({ project: theProject.id }), 
+          { operations: '[]' },
+          function(o) {},
+          "json"
+        );
+      } else {
+        self._cancelAll();
+      }
+    }
+  }
+  
   if (this._data.processes.length && !this._timerID) {
     this._timerID = window.setTimeout(function() {
       self._timerID = null;