diff --git a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/settings/model/CExternalSettingsManager.java b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/settings/model/CExternalSettingsManager.java
index 99998c7f330..5829e97ea17 100644
--- a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/settings/model/CExternalSettingsManager.java
+++ b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/settings/model/CExternalSettingsManager.java
@@ -132,6 +132,9 @@ public class CExternalSettingsManager implements ICExternalSettingsListener, ICP
 		
 		private CExternalSettingsContainer fContainer;
 
+		/** Stash error messages so we're not too noisy if things go wrong */
+		private static Set<String> failingProvidersMessages;
+
 		private ContainerDescriptor(FactoryDescriptor factoryDr,
 				String containerId, 
 				IProject project,
@@ -141,12 +144,17 @@ public class CExternalSettingsManager implements ICExternalSettingsListener, ICP
 			try {
 				fContainer = fFactoryDr.getFactory().createContainer(containerId, project, cfgDes, previousSettings);
 			} catch (CoreException e) {
-				CCorePlugin.log(e);
+				if (failingProvidersMessages == null)
+					failingProvidersMessages = new HashSet<String>();
+				// only report the error once per session
+				if (!failingProvidersMessages.contains(e.getMessage()))
+					CCorePlugin.log(e.getMessage());
+				failingProvidersMessages.add(e.getMessage());
 			}
 			if(fContainer == null)
 				fContainer = NullContainer.INSTANCE;
 		}
-		
+
 		public CExternalSetting[] getExternalSettings(){
 			if(fHolder == null){
 				fHolder = new CExternalSettingsHolder();
diff --git a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/settings/model/ExtensionContainerFactory.java b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/settings/model/ExtensionContainerFactory.java
index 4d18dc4c09b..de5aa63d1ff 100644
--- a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/settings/model/ExtensionContainerFactory.java
+++ b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/settings/model/ExtensionContainerFactory.java
@@ -179,7 +179,9 @@ public class ExtensionContainerFactory extends CExternalSettingContainerFactoryW
 		CExtensionSettingProviderDescriptor dr = getProviderDescriptorMap().get(id);
 		if(dr != null)
 			return dr.getContainer(project, cfgDes, previousSettings);
-		return CExternalSettingsManager.NullContainer.INSTANCE;
+		// Notify the manager that there's no external settings manager matching id.
+		throw new CoreException(CCorePlugin.createStatus("External settings provider: \"" + id + "\" couldn't be found for " +  //$NON-NLS-1$//$NON-NLS-2$
+			cfgDes.getProjectDescription().getProject() + ":"+cfgDes.getName())); //$NON-NLS-1$
 	}
 	
 	public static String[] getReferencedProviderIds(ICConfigurationDescription cfg){